Departamento de Físicahttps://repositorio.unifesp.br/handle/11600/413212021-06-18T10:09:13Z2021-06-18T10:09:13ZRelatividade geral no espaço-tempo bidimensional e tridimensionalJamaica, Juan David Fonseca [UNIFESP]https://repositorio.unifesp.br/handle/11600/588802021-01-06T13:41:19Z2020-10-05T00:00:00ZRelatividade geral no espaço-tempo bidimensional e tridimensional
Jamaica, Juan David Fonseca [UNIFESP]
Em este trabalho é desenvolvido uma explicação mais exaustiva e pedagógica do artigo: General relativity in two and threedimensional space-times (Peter Collas, 1997) que, embora seja
uma pesquisa muito completa e rigorosa, por razões de sínteses os aspetos físicos e matemáticos
são mencionados mas não esclarecidos com detalhe. O comportamento da relatividade geral em
um Espaço-Tempo bidimensional e tridimensional é o tópico central a discutir. Como resultado
no caso bidimensional, foi mostrado que a ausência da matéria é independente da curvatura intrínseca da geometria Espaço-Temporal. No caso tridimensional foi mostrado que: se o espaço
estiver vazio a geometria tem que ser plana; existe uma solução interior que corresponde a um
universo de De Sitter; distribuições de massa nita garantem uma anulação da pressão. Finalmente, o modelo cosmológico para um universo de poeira é caracterizado por uma expansão do
tipo Hubble que corresponde ao modelo de Milne.; In this work, it has been developed a more exhaustive and pedagogical explanation of the article: General relativity in two and threedimensional space-times (Peter Collas, 1997) which,
although it is a very complete and rigorous research, for synthesis rations the physical and
mathematical aspects are mentioned but not clari ed in detail. The behavior of general relativity in a two-dimensional and three-dimensional space-time is the central topic to be discussed.
As a result in the two-dimensional case, it was shown that the absence of matter is independent of the intrinsic curvature of space-time geometry. In the three-dimensional case, it was
shown that: if the space is empty, the geometry has to be at; there is an interior solution
that corresponds to a De Sitter universe; nite mass distributions guarantee an elimination of
pressure. Finally, the cosmological model for a dust universe is characterized by an expansion
of the Hubble type that corresponds to Milne's model.
2020-10-05T00:00:00ZA nucleossíntese no universo primordialCampos, Gabriela Camargo [UNIFESP]https://repositorio.unifesp.br/handle/11600/588792020-12-16T20:46:58Z2020-10-09T00:00:00ZA nucleossíntese no universo primordial
Campos, Gabriela Camargo [UNIFESP]
Neste trabalho, concentramos no estudo da Nucleossíntese Primordial, abordando tanto os
processos nucleares nela envolvidos, como sua importância para a história do Universo como
o conhecemos, e para o desenvolvimento do Modelo Cosmológico Padrão. Optamos pela
descrição desse modelo a partir da sua origem como decorrência da Teoria da Relatividade
Geral. Nesse percurso, adentramos no tema do Universo Primordial, onde a nucleossíntese
dos elementos químicos leves e suas abundâncias têm um papel fundamental na evolução do
Universo. Por fim, apresentamos os principais métodos atuais de medida das abundâncias
destes elementos, realizando uma comparação entre as previsões teóricas e os resultados
observacionais.; In this work, we focus on the study of Primordial Nucleosynthesis, addressing the nuclear
processes involved in it, as well as its importance for the history of the Universe as we know
it, and for the development of the Standard Cosmological Model. We chose to describe this
model from its origin as a result of the Theory of General Relativity. Along this path, we
get into the theme of the Primordial Universe, where the nucleosynthesis of light chemical
elements and their abundance plays a fundamental role in the evolution of the Universe.
Finally, we present the main current methods of measuring these abundances, making a
comparison between theoretical predictions and observational results.
2020-10-09T00:00:00ZÓrbitas relativísticas usando o Princípio de Mínima AçãoPossamai, Daniel de Macedo [UNIFESP]https://repositorio.unifesp.br/handle/11600/588782020-12-16T20:38:57Z2020-10-09T00:00:00ZÓrbitas relativísticas usando o Princípio de Mínima Ação
Possamai, Daniel de Macedo [UNIFESP]
O presente trabalho apresenta e analisa gráficos que mostram a diferença de
trajetória nas órbitas de uma partícula sob aproximações da mecânica Newtoniana e
sob aplicação da Teoria da Relatividade Geral, a última utilizando a métrica de
Schwarzschild e a métrica de Kerr. Porém, antes da apresentação dos gráficos, os
fundamentos teóricos de como obter as equações de movimento serão introduzidos.
Para tanto, conceitos como o Princípio de Mínima Ação, definição da Lagrangeana e
aplicação da equação de Euler-Lagrange serão utilizados. Através dos fundamentos
teóricos, obtemos as equações de movimento na forma de um sistema de equações
diferenciais. Para solução deste sistema de equações é apresentado um método
utilizando álgebra computacional, o qual possibilita a solução numérica das equações
de movimento.; In this work, we analyze the differences of the trajectories of particles around
massive objects under Newtonian and relativistic approaches, the latter using the
Schwarzchild and the Kerr metrics. However, before presenting the orbit’s graphs, we present the theoretical foundations of how to obtain the equations of motion.
Concepts such as the Principle of Least Action and the Lagrangian definition of
the problem are presented, after which we express the Euler-Lagrange equations. To solve this system of equations, we present a computational method using computer algebra, so that the numerical solution of the equations of motion is possible.
2020-10-09T00:00:00ZMétrica de Kerr e buracos negros astrofísicos: um estudo abrangenteSiqueira, Pedro Henrique Croti [UNIFESP]https://repositorio.unifesp.br/handle/11600/588772020-12-16T20:29:48Z2020-10-09T00:00:00ZMétrica de Kerr e buracos negros astrofísicos: um estudo abrangente
Siqueira, Pedro Henrique Croti [UNIFESP]
Este trabalho realiza um estudo fenomenológico abrangente acerca da
chamada métrica de Kerr, explicitando suas características e sua relevância
astrofísica. A Teoria da Relatividade Geral utiliza de equações diferenciais nãolineares (chamadas equações de Einstein) para descrever a relação entre a geometria
do espaço-tempo e o conteúdo de matéria e energia que este possui. Uma das
soluções exatas dessas equações é chamada métrica de Kerr que descreve a região
exterior a um buraco negro rotante e sem carga elétrica. Analisa-se, neste trabalho,
as superfícies e órbitas que surgem a partir dessa métrica e discute-se o motivo de
acreditar-se que todos os buracos negros astrofísicos são descritos por ela.; This work carries out a phenomenological study covering the so-called Kerr metric,
explaining its features and its astrophysical relevance. The General Theory of
Relativity uses nonlinear differential equations (called Einstein's equations) to describe
the relationship between the geometry of spacetime and the content of matter and
energy it has. One of the exact solutions to these equations is called the Kerr metric,
which describes the outer region of a rotating black hole with no electric charge. In this
work, we analyze the surfaces and orbits that arise from this metric and discuss the
reason for believing that all astrophysical black holes are generated by it.
2020-10-09T00:00:00ZOscilações acústicas de bárions e sua importânciaLopes, Celso Oviedo da Silva [UNIFESP]https://repositorio.unifesp.br/handle/11600/588762020-12-16T20:31:40Z2020-10-09T00:00:00ZOscilações acústicas de bárions e sua importância
Lopes, Celso Oviedo da Silva [UNIFESP]
Embora frequentemente formulada em termos de desvendar a natureza da
energia escura, a cosmologia atual também pode ser vista como uma revolução nas
medições de distância. Pela primeira vez, começamos a sondar com precisão a
história da expansão do cosmos muito além do universo local, ou seja, em redshifts
intermediários e altos (z > 1). Na evolução da escala de distâncias, um papel
essencial foi desempenhado pelas supernovas do tipo Ia (SNe Ia) que possibilitaram
uma mudança paradigmática na cosmologia moderna: a descoberta da expansão
acelerada do universo. Junto com essa descoberta, outros fenômenos também são
relevantes para a compreensão da composição e evolução do universo observado.
Além das anisotropias de fundo cósmico de microondas (CMB), atenção especial
tem sido dada às chamadas oscilações acústicas dos bárions (BAO). O fenômeno
BAO envolve medidas da distribuição espacial das galáxias para determinar a taxa
de crescimento das estruturas cósmicas que ocorrem no universo em expansão. Os padrões formados pela distribuição das galáxias contêm informações sobre como a estrutura cósmica se expandiu a partir de pequenas flutuações iniciais. Este tipo de agrupamento define uma "régua padrão" de origem estatística entre galáxias e outros objetos celestes e pode ser usado para reconstruir a expansão do universo. Neste TCC, iremos nos concentrar no BAO obtido de um conjunto de galáxias observadas pelo Sloan Digital Sky Survey (SDDS). A detecção de um pico na função de correlação radial indica evidências indiretas da existência das oscilações acústicas dos bárions, ou seja, flutuações na densidade da matéria visível. O nosso principal objetivo é fazer uma revisão da física envolvida nas oscilações acústicas dos bárions, com particular ênfase nos principais projetos em curso visando a medição do BAO longitudinal e transversal.; Although often formulated in terms of unraveling the nature of dark energy,
current cosmology can also be viewed as a revolution in distance measurements. For
the first time, we are beginning to probe with precision the history of the expansion of
the cosmos far beyond the local universe, that is, in intermediate and high redshifts
(z>1). In the evolution of the distance scale, an essential role was played by type Ia
(SNe Ia) supernovae that enabled a paradigmatic change in modern cosmology: the
discovery of the accelerated expansion of the universe. Along with this discovery,
other phenomena are also relevant for understanding the observed universe's
composition and evolution. In addition to the anisotropies of cosmic microwave
background (CMB), special attention has been given to the so-called baryons
acoustic oscillations (BAO). The BAO phenomenon involves measures of galaxies'
spatial distribution to determine the rate of growth of cosmic structures occurring in
the expanding universe. The patterns formed by the distribution of galaxies contain
information about how the cosmic structure expanded from small initial fluctuations.
This type of grouping defines a "standard ruler" of statistical origin between galaxies
and other celestial objects and can be used to reconstruct the universe's expansion. In this TCC, we will focus on the BAO obtained from a set of galaxies
observed by the Sloan Digital Sky Survey (SDDS). The detection of a peak in the
radial correlation function indicates indirect evidence for the existence of acoustic
oscillations of baryons, that is, fluctuations in the density of visible matter. Our main
objective is to review the physics involved in the baryons' acoustic oscillations, with
particular emphasis on the main projects in progress aiming at the measurement of
longitudinal and transversal BAO.
2020-10-09T00:00:00ZMass density and size estimates for spiral galaxies using general relativityMagalhaes, N. S. [UNIFESP]Cooperstock, F. I.https://repositorio.unifesp.br/handle/11600/582842020-09-01T13:21:28Z2017-01-01T00:00:00ZMass density and size estimates for spiral galaxies using general relativity
Magalhaes, N. S. [UNIFESP]; Cooperstock, F. I.
Rotation curves of spiral galaxies reveal a physical phenomenon that has been seen to lack a satisfactory scientific explanation: velocities of stars far from the nucleus are high and approximately constant. In the context of Newtonian dynamics, the existence of a new kind of matter (dark matter) is assumed, which, when added to the usual observed matter, would account for the phenomenon; however, the nature of such dark matter is unknown and it was never detected. There are other ongoing investigations of the phenomenon, such as MOND and emergent gravity. In this work we present new results from another approach, in which general relativity is employed to approximate a galaxy by an axially-symmetric, pressure-less fluid in stationary rotation, yielding an expression for its rotation curve and mass density. We apply this model to data of four galaxies: NGC 2403, NGC 2903, NGC 5055 and the Milky Way. We obtain mass density contours of these galaxies which we compare to observational data, a procedure that could open a new window for investigating galactic structure. In our Solar neighborhood, we found a mass density and density fall-off fitting observational data satisfactorily, addressing a critique to the model by Fuchs and Phleps. Using a threshold density apparently related to the observed optical zone of a galaxy, the model had already indicated that the Milky Way could be larger than had been believed to be the case. To our knowledge, this was the only such existing theoretical indication ever presented. Recent observational results by Xu et al. have confirmed that theoretical prediction, which we fortify here using a large set of observational data. Galactic masses are seen to be higher than the baryonic mass determined from observations but lower than those deduced from the approaches relying upon dark matter in a Newtonian context. We also calculate the non-luminous fraction of matter for our sample of galaxies and present possible general relativistic explanations for this. The evidence points to general relativity playing a significant role in the explanation of the phenomenon.
2017-01-01T00:00:00ZLight sensitive memristor with bi-directional and wavelength-dependent conductance controlMaier, P.Hartmann, F.Dias, M. Rebello Sousa [UNIFESP]Emmerling, M.Schneider, C.Castelano, L. K. [UNIFESP]Kamp, M.Marques, G. E. [UNIFESP]Lopez-Richard, V. [UNIFESP]Worschech, L.Hoefling, S.https://repositorio.unifesp.br/handle/11600/575462020-08-14T13:44:14Z2016-01-01T00:00:00ZLight sensitive memristor with bi-directional and wavelength-dependent conductance control
Maier, P.; Hartmann, F.; Dias, M. Rebello Sousa [UNIFESP]; Emmerling, M.; Schneider, C.; Castelano, L. K. [UNIFESP]; Kamp, M.; Marques, G. E. [UNIFESP]; Lopez-Richard, V. [UNIFESP]; Worschech, L.; Hoefling, S.
We report the optical control of localized charge on positioned quantum dots in an electro-photo-sensitive memristor. Interband absorption processes in the quantum dot barrier matrix lead to photo-generated electron-hole-pairs that, depending on the applied bias voltage, charge or discharge the quantum dots and hence decrease or increase the conductance. Wavelength-dependent conductance control is observed by illumination with red and infrared light, which leads to charging via interband and discharging via intraband absorption. The presented memristor enables optical conductance control and may thus be considered for sensory applications in artificial neural networks as light-sensitive synapses or optically tunable memories. Published by AIP Publishing.
2016-01-01T00:00:00ZMatter-parity as a residual gauge symmetry: Probing a theory of cosmological dark matterAlves, Alexandre [UNIFESP]Arcadi, GiorgioDong, P. V.Duarte, LauraQueiroz, Farinaldo S.Valle, Jose W. F.https://repositorio.unifesp.br/handle/11600/573682020-08-04T14:43:58Z2017-01-01T00:00:00ZMatter-parity as a residual gauge symmetry: Probing a theory of cosmological dark matter
Alves, Alexandre [UNIFESP]; Arcadi, Giorgio; Dong, P. V.; Duarte, Laura; Queiroz, Farinaldo S.; Valle, Jose W. F.
We discuss a non-supersymmetric scenario which addresses the origin of the matter-parity symmetry, P-M = (-1)(3(B-L)+2s), leading to a viable Dirac fermion dark matter candidate. Implications to electroweak precision, muon anomalous magnetic moment, flavor changing interactions, lepton flavor violation, dark matter and collider physics are discussed in detail. We show that this non-supersymmetric model is capable of generating the matter-parity symmetry in agreement with existing data with gripping implications to particle physics and cosmology. (C) 2017 The Author(s). Published by Elsevier B.V.
2017-01-01T00:00:00ZExercise and sport do not trigger seizures in children and adolescents with epilepsy in school settingsVancini, Rodrigo LuizAndrade, Marilia dos Santos [UNIFESP]Vancini-Campanharo, Cassia ReginaBarbosa de Lira, Claudio Andrehttps://repositorio.unifesp.br/handle/11600/572182020-08-04T14:36:55Z2017-01-01T00:00:00ZExercise and sport do not trigger seizures in children and adolescents with epilepsy in school settings
Vancini, Rodrigo Luiz; Andrade, Marilia dos Santos [UNIFESP]; Vancini-Campanharo, Cassia Regina; Barbosa de Lira, Claudio Andre
2017-01-01T00:00:00ZAbsorption and production cross sections of K and K*Torres, A. MartinezKhemchandani, Kanchan Pradeepkumar [UNIFESP]Abreu, L. M.Navarra, F. S.Nielsen, M.https://repositorio.unifesp.br/handle/11600/558372020-07-20T17:41:27Z2018-01-01T00:00:00ZAbsorption and production cross sections of K and K*
Torres, A. Martinez; Khemchandani, Kanchan Pradeepkumar [UNIFESP]; Abreu, L. M.; Navarra, F. S.; Nielsen, M.
We have computed the isospin and spin averaged cross sections of the processes pi K* -> rho K and rho K* -> pi K, which are crucial in the determination of the abundances of K* and K in heavy ion collisions. Improving previous calculations, we have considered several mechanisms which were missing, such as the exchange of axial and vector resonances (K-1(1270), K-2*(1430), h(1)(1170), etc.) and also other processes such as pi K* -> omega K; phi K and omega K*, phi K* -> pi K. We find that some of these mechanisms give important contributions to the cross section.
2018-01-01T00:00:00ZCollider detection of dark matter electromagnetic anapole momentsAlves, Alexandre [UNIFESP]Santos, A. C. O.Sinha, Kuverhttps://repositorio.unifesp.br/handle/11600/558152020-07-20T17:42:39Z2018-01-01T00:00:00ZCollider detection of dark matter electromagnetic anapole moments
Alves, Alexandre [UNIFESP]; Santos, A. C. O.; Sinha, Kuver
Dark matter that interacts with the Standard Model by exchanging photons through higher multipole interactions occurs in a wide range of both strongly and weakly coupled hidden sector models. We study the collider detection prospects of these candidates, with a focus on Majorana dark matter that couples through the anapole moment. The study is conducted at the effective field theory level with the mono-Z signature incorporating varying levels of systematic uncertainties at the high-luminosity LHC. The projected collider reach on the anapole moment is then compared to the reach coming from direct detection experiments like LZ. Finally, the analysis is applied to a weakly coupled completion with leptophilic dark matter.
2018-01-01T00:00:00ZExclusive vector meson photoproduction with a leading baryon in photon-hadron interactions at hadronic collidersCarvalho, F. [UNIFESP]Goncalves, V. P.Navarra, F. S.Spiering, D.https://repositorio.unifesp.br/handle/11600/556472020-07-20T17:43:59Z2018-01-01T00:00:00ZExclusive vector meson photoproduction with a leading baryon in photon-hadron interactions at hadronic colliders
Carvalho, F. [UNIFESP]; Goncalves, V. P.; Navarra, F. S.; Spiering, D.
Exclusive vector meson photoproduction associated with a leading baryon (B = n, Delta(+), Delta(0)) in pp and pA collisions at RHIC and LHC energies is investigated using the color dipole formalism and taking into account nonlinear effects in the QCD dynamics. In particular, we compute the cross sections for rho, phi and J/Psi production together with a Delta and compare the predictions with those obtained for a leading neutron. Our results show that the V + Delta cross section is almost 30% of the V + n one. Our results also show that a future experimental analysis of these processes is, in principle, feasible and can be useful to study leading particle production.
2018-01-01T00:00:00ZUpdate on J/psi regeneration in a hadron gasAbreu, L. M.Khemchandani, Kanchan Pradeepkumar [UNIFESP]Torres, A. MartinezNavarra, F. S.Nielsen, M.https://repositorio.unifesp.br/handle/11600/556432020-07-20T17:44:16Z2018-01-01T00:00:00ZUpdate on J/psi regeneration in a hadron gas
Abreu, L. M.; Khemchandani, Kanchan Pradeepkumar [UNIFESP]; Torres, A. Martinez; Navarra, F. S.; Nielsen, M.
In heavy-ion collisions, after the quark-gluon plasma there is a hadronic gas phase. Using effective Lagrangians, we study the interactions of charmed mesons which lead to J/psi production and absorption in this gas. We update and extend previous calculations introducing strange meson interactions and also including the interactions mediated by the recently measured exotic charmonium resonances Z(3900) and Z(4025). These resonances open new reaction channels for the J/psi, which could potentially lead to changes in its multiplicity. We compute the J/psi production cross section in processes such as D-(s)(*) + (D) over bar(*) -> J/psi + (pi, rho, K, K*) and also the J/psi absorption cross section in the corresponding inverse processes. Using the obtained cross sections as input to solve the appropriate rate equation, we conclude that the interactions in the hadron gas phase lead to a 20-24% reduction of the J/psi abundance. Within the uncertainties of the calculation, this reduction is the same at the Relativistic Heavy Ion Collider and the large Hadron Collider.
2018-01-01T00:00:00ZSynthesis and characterization of aminolevulinic acid gold nanoparticles: Photo and sonosensitizer agent for atherosclerosisGoncalves, Karina de Oliveira [UNIFESP]Vieira, Daniel Perez [UNIFESP]Courrol, Lilia Coronato [UNIFESP]https://repositorio.unifesp.br/handle/11600/556212020-07-20T16:30:58Z2018-01-01T00:00:00ZSynthesis and characterization of aminolevulinic acid gold nanoparticles: Photo and sonosensitizer agent for atherosclerosis
Goncalves, Karina de Oliveira [UNIFESP]; Vieira, Daniel Perez [UNIFESP]; Courrol, Lilia Coronato [UNIFESP]
Photodynamic and sonodynamic therapies (PDT and SDT, respectively) are emerging as new atherosclerosis treatments. The subsequent generation of free radicals by activated photo and sonosensitizers can lead to apoptotic cell death. The use of gold nanoparticles (AuNPs) as the vehicle for a sensitizer delivery improves reactive oxygen species formation and sensitizer performance. In this study gold nanoparticles functionalized with polyethylene glycol (PEG) were synthesized mixing delta-aminolevulinic acid (ALA) with tetrachloroauric (III) acid in milliQ water solution followed by photo reduction with 300W xenon lamp. The synthesized ALA: AuNPs were characterized by UV/vis optical absorption, zeta potential and electron microscopy. The mean particle size of spherical ALA: AuNP was similar to 18 nm, with a polydispersity index of 0.437. Singlet oxygen generation efficiency was measured using the trap molecule 1,3-diphenylisobenzofuran. ALA: AuNPs and DPBF were irradiated with 590 nm LED, or pulse ultrasound irradiation (1 W/cm(2) with 1.0 MHz), and consumption of the DPBF was monitored over time by the absorption and emission spectra. The results showed that he gold nanoparticles generate singlet oxygen during light and ultrasound irradiations. THP-1 cells differentiated into macrophages cytotoxicity test were described and was found the half maximal inhibitory concentration (IC50) values similar to 36 nM for ALA: AuNPs. Increase in the fluorescence intensity of PpIX extracted from macrophages incubated with ALA: AuNPs indicating stable encapsulation of ALA into gold nanoparticles and further conversion to PpIX. The potential use of ALA: AuNps as a sensitizer for photo and sonodynamic therapies were investigated. ALA: AuNPs mediated SDT was more effective than PDT. SDT with ALA: AuNPs induced the reduction of macrophage viability in similar to 87,5% in only 2 min. The mechanism underlying SDT-induced apoptosis involves the generation of singlet oxygen. The results indicate that ALA: AuNPs can be used as a novel photo and sonosensitizer for atherosclerosis.
2018-01-01T00:00:00ZThe energy density distribution of an ideal gas and Bernoulli's equationsSantos, Leonardo Sioufi Fagundes dos [UNIFESP]https://repositorio.unifesp.br/handle/11600/556192020-07-20T16:30:58Z2018-01-01T00:00:00ZThe energy density distribution of an ideal gas and Bernoulli's equations
Santos, Leonardo Sioufi Fagundes dos [UNIFESP]
This work discusses the energy density distribution in an ideal gas and the consequences of Bernoulli's equation and the corresponding relation for compressible fluids. The aim of this work is to study how Bernoulli's equation determines the energy flow in a fluid, although Bernoulli's equation does not describe the energy density itself. The model from molecular dynamic considerations that describes an ideal gas at rest with uniform density is modified to explore the gas in motion with non-uniform density and gravitational effects. The difference between the component of the speed of a particle that is parallel to the gas speed and the gas speed itself is called 'parallel random speed'. The pressure from the 'parallel random speed' is denominated as parallel pressure. The modified model predicts that the energy density is the sum of kinetic and potential gravitational energy densities plus two terms with static and parallel pressures. The application of Bernoulli's equation and the corresponding relation for compressible fluids in the energy density expression has resulted in two new formulations. For incompressible and compressible gas, the energy density expressions are written as a function of stagnation, static and parallel pressures, without any dependence on kinetic or gravitational potential energy densities. These expressions of the energy density are the main contributions of this work. When the parallel pressure was uniform, the energy density distribution for incompressible approximation and compressible gas did not converge to zero for the limit of null static pressure. This result is rather unusual because the temperature tends to zero for null pressure. When the gas was considered incompressible and the parallel pressure was equal to static pressure, the energy density maintained this unusual behaviour with small pressures. If the parallel pressure was equal to static pressure, the energy density converged to zero for the limit of the null pressure only if the gas was compressible. Only the last situation describes an intuitive behaviour for an ideal gas.
2018-01-01T00:00:00ZBayesian Inference Applied to Pulsar's ModelsMarinho, Rubens M., Jr.de Oliveira, Heitor O.Magalhaes, Nadja S. [UNIFESP]Valentim, Rodolfo [UNIFESP]Coelho, Jaziel G.Alves, Marcio E. S.https://repositorio.unifesp.br/handle/11600/554602020-07-17T14:03:31Z2017-01-01T00:00:00ZBayesian Inference Applied to Pulsar's Models
Marinho, Rubens M., Jr.; de Oliveira, Heitor O.; Magalhaes, Nadja S. [UNIFESP]; Valentim, Rodolfo [UNIFESP]; Coelho, Jaziel G.; Alves, Marcio E. S.
The goal of this work is to apply Bayesian statistics to the problem of pulsars in order to compute the Bayes factor and investigate which one among different EoS could better fit known pulsar data, regarding the rate of decrease of the angular velocity versus the angular velocity itself. We also find the posterior distribution and the best fit for some relevant parameters of the pulsar like the mass and the magnetic field.
2017-01-01T00:00:00ZBraking Indices of Pulsars Obtained in the Presence of an Effective ForceMagalhaes, Nadja S. [UNIFESP]Okada, Andre S. [UNIFESP]Frajuca, Carloshttps://repositorio.unifesp.br/handle/11600/554592020-07-17T14:03:31Z2017-01-01T00:00:00ZBraking Indices of Pulsars Obtained in the Presence of an Effective Force
Magalhaes, Nadja S. [UNIFESP]; Okada, Andre S. [UNIFESP]; Frajuca, Carlos
The theoretical calculation of braking indices of pulsars is still an open problem. In this work we present a study on this issue which adapts the model that assumes that pulsars are rotating magnetic dipoles by introducing a compensating component in the energy conservation equation of the system. Such component relates to an effective force that varies with the first power of the tangential velocity of the pulsar's crust. We tested the proposed model using data available
2017-01-01T00:00:00ZA Model for the Braking Indices of Pulsarsde Oliveira, Heitor O.Marinho, Rubens M., Jr.Magalhaes, Nadja S. [UNIFESP]https://repositorio.unifesp.br/handle/11600/554582020-07-17T14:03:31Z2017-01-01T00:00:00ZA Model for the Braking Indices of Pulsars
de Oliveira, Heitor O.; Marinho, Rubens M., Jr.; Magalhaes, Nadja S. [UNIFESP]
Stars known as pulsars are generally modeled as magnetized spheres made of neutrons with high rotation frequency. It is known that such stars are spinning down and this braking is measured by a parameter, n, known as braking index. For the canonical model such parameter should have a single value for all pulsars: n = 3. However, from observations it is known that n diverges from 3. In this work, differently from the canonical model, we have hypothesized the existence of a variation of the moment of inertia of the star through a time-varying radius. Using energy conservation we find the values for the variation of the radius of our pulsar sample. Our results indicate that it may be reasonable to consider that the radius of pulsars can be changing with time.
2017-01-01T00:00:00ZAugury of darkness: the low-mass dark Z ' portalAlves, Alexandre [UNIFESP]Arcadi, GiorgioMambrini, YannProfumo, StefanoQueiroz, Farinaldo S.https://repositorio.unifesp.br/handle/11600/547052020-07-17T14:40:55Z2017-01-01T00:00:00ZAugury of darkness: the low-mass dark Z ' portal
Alves, Alexandre [UNIFESP]; Arcadi, Giorgio; Mambrini, Yann; Profumo, Stefano; Queiroz, Farinaldo S.
Dirac fermion dark matter models with heavy Z ' mediators are subject to stringent constraints from spin-independent direct searches and from LHC bounds, cornering them to live near the Z ' resonance. Such constraints can be relaxed, however, by turning off the vector coupling to Standard Model fermions, thus weakening direct detection bounds, or by resorting to light Z ' masses, below the Z pole, to escape heavy resonance searches at the LHC. In this work we investigate both cases, as well as the applicability of our findings to Majorana dark matter. We derive collider bounds for light Z ' gauge bosons using the CLS method, spin-dependent scattering limits, as well as the spin-independent scattering rate arising from the evolution of couplings between the energy scale of the mediator mass and the nuclear energy scale, and indirect detection limits. We show that such scenarios are still rather constrained by data, and that near resonance they could accommodate the gamma-ray GeV excess in the Galactic center.
2017-01-01T00:00:00ZStacking machine learning classifiers to identify Higgs bosons at the LHCAlves, A. [UNIFESP]https://repositorio.unifesp.br/handle/11600/545352020-07-13T11:53:19Z2017-01-01T00:00:00ZStacking machine learning classifiers to identify Higgs bosons at the LHC
Alves, A. [UNIFESP]
Machine learning (ML) algorithms have been employed in the problem of classifying signal and background events with high accuracy in particle physics. In this paper, we compare the performance of a widespread ML technique, namely, stacked generalization, against the results of two state-of-art algorithms: (1) a deep neural network (DNN) in the task of discovering a new neutral Higgs boson and (2) a scalable machine learning system for tree boosting, in the Standard Model Higgs to tau leptons channel, both at the 8 TeV LHC. In a cut-and-count analysis, stacking three algorithms performed around 16% worse than DNN but demanding far less computation efforts, however, the same stacking outperforms boosted decision trees. Using the stacked classifiers in a multivariate statistical analysis (MVA), on the other hand, significantly enhances the statistical significance compared to cut-and-count in both Higgs processes, suggesting that combining an ensemble of simpler and faster ML algorithms with MVA tools is a better approach than building a complex state-of-art algorithm for cut-and-count.
2017-01-01T00:00:00ZConstraining Elko dark matter at the LHC with monophoton eventsAlves, Alexandre [UNIFESP]Dias, M. [UNIFESP]de Campos, F.Duarte, L.Hoff da Silva, J. M.https://repositorio.unifesp.br/handle/11600/541622020-07-08T13:09:43Z2018-01-01T00:00:00ZConstraining Elko dark matter at the LHC with monophoton events
Alves, Alexandre [UNIFESP]; Dias, M. [UNIFESP]; de Campos, F.; Duarte, L.; Hoff da Silva, J. M.
A mass-dimension-one fermion, also known as Elko, constitutes a dark-matter candidate which might interact with photons at the tree level in a specific fashion. In this work, we investigate the constraints imposed by unitarity and LHC data on this type of interactions using the search for new physics in monophoton events. We found that Elkos which can explain the dark matter relic abundance mainly through electromagnetic interactions are excluded at the 95% CL by the 8TeV LHC data for masses up to 1TeV. Copyright (C) EPLA, 2018
2018-01-01T00:00:00ZTm3+ doped barium molybdate: A potential long-lasting blue phosphorde Azevedo Marques, Ana Paula [UNIFESP]Kunzel, Roseli [UNIFESP]Umisedo, Nancy K.Latini, Renato Mazin [UNIFESP]Yoshimura, Elizabeth MateusOkuno, Emicohttps://repositorio.unifesp.br/handle/11600/541122020-07-08T13:09:38Z2018-01-01T00:00:00ZTm3+ doped barium molybdate: A potential long-lasting blue phosphor
de Azevedo Marques, Ana Paula [UNIFESP]; Kunzel, Roseli [UNIFESP]; Umisedo, Nancy K.; Latini, Renato Mazin [UNIFESP]; Yoshimura, Elizabeth Mateus; Okuno, Emico
Molybdates have applications in various fields such as phosphors, optical fibers, scintillators, magnets, sensors and catalysts. Thulium ion is an excellent blue activator and plays an important role in the design of persistent luminescent materials. This paper reports the investigation of the structural and luminescent properties of Barium Thulium Molybdate (Ba1-xTmx)MoO4 microcrystals (with x = 0, 0.01 or 0.03). The scheelite-type crystalline structure was identified from XRD and Raman studies. Under ultraviolet (359 nm) excitation, photoluminescence (PL) spectra present the characteristic emission bands at 453 nm and 545 nm which are due to the D-1(2) -> F-3(4) and D-1(2) -> H-3(4,5) transitions, respectively, from Tm3+ ions. Thermoluminescence (TL) measurements were performed with powdered samples previously irradiated with beta radiation. The depth of traps, associated with trap levels located inside the band-gap, was determined from TL data using different methods of glow curve analysis. The kinetic parameters, determined from thermoluminescent glow curves, provide evidence about a possible persistent luminescence emission from the (Ba0.97Tm0.03)MoO4 sample. This is a potential blue-light or ultraviolet long-lasting phosphor, with a trapping level lifetime, at room-temperature (300 K), of about 6 days. (C) 2017 Elsevier B.V. All rights reserved.
2018-01-01T00:00:00ZCan measurement of the fluorescence lifetime of extracted blood PPIX predict atherosclerosis?Sicchieri, Leticia B.Da Silva, Monica N. [UNIFESP]Samad, Ricardo E.Courrol, Lilia C. [UNIFESP]https://repositorio.unifesp.br/handle/11600/541042020-07-08T13:09:37Z2018-01-01T00:00:00ZCan measurement of the fluorescence lifetime of extracted blood PPIX predict atherosclerosis?
Sicchieri, Leticia B.; Da Silva, Monica N. [UNIFESP]; Samad, Ricardo E.; Courrol, Lilia C. [UNIFESP]
In this work, fluorescence lifetime has been used to analyze protoporphyrin IX (PPIX) extracted from blood for diagnosing atherosclerosis. A total of 10 adult white male rabbits (New Zealand) were divided into the control group (CG), with a normal diet, and the experimental group (EG), subjected to a diet containing 1% cholesterol. Blood samples were collected from the animals, and protoporphyrin IX was extracted from the blood using acetone. The PPIX fluorescence lifetime (PPIXFL) was measured using time-correlated single photon counting, after excitation at 403 nm from a pulsed laser diode. It was found that the PPIX emission intensity was enhanced in the animals that had received a hypercholesterolemic diet. The CG and EG animal's fluorescence decays were fitted by three exponentials and the mean lifetimes were 4.0 ns and 9.5 ns, respectively. This lifetime dependence resulted in a calibration curve that allows the determination of the PPIX concentration with a temporal measurement. The obtained results show that fluorescence lifetime can potentially be used as a noninvasive, simple, rapid, and sensitive tool in atherosclerosis diagnosis.
2018-01-01T00:00:00ZA Grid of Synthetic Spectra for Hot DA White Dwarfs and Its Application in Stellar Population SynthesisLevenhagen, Ronaldo S. [UNIFESP]Diaz, Marcos P.Coelho, Paula R. T.Hubeny, Ivanhttps://repositorio.unifesp.br/handle/11600/536022020-06-26T16:30:32Z2017-01-01T00:00:00ZA Grid of Synthetic Spectra for Hot DA White Dwarfs and Its Application in Stellar Population Synthesis
Levenhagen, Ronaldo S. [UNIFESP]; Diaz, Marcos P.; Coelho, Paula R. T.; Hubeny, Ivan
In this work we present a grid of LTE and non-LTE synthetic spectra of hot DA white dwarfs (WDs). In addition to its usefulness for the determination of fundamental stellar parameters of isolated WDs and in binaries, this grid will be of interest for the construction of theoretical libraries for stellar studies from integrated light. The spectral grid covers both a wide temperature and gravity range, with 17,000 K <= T-eff <= 100,000 K and 7.0 <= log g <= 9.5. The stellar models are built for pure hydrogen and the spectra cover a wavelength range from 900 angstrom to 2.5 mu m. Additionally, we derive synthetic HST/ACS, HST/WFC3, Bessel UBVRI, and SDSS magnitudes. The grid was also used to model integrated spectral energy distributions of simple stellar populations and our modeling suggests that DAs might be detectable in ultraviolet bands for populations older than similar to 8 Gyr.
2017-01-01T00:00:00ZMaximum Entropy Inferences on the Axion Mass in Models with Axion-Neutrino InteractionAlves, Alexandre [UNIFESP]Dias, Alex Gomesda Silva, Robertohttps://repositorio.unifesp.br/handle/11600/514932019-08-19T11:50:13Z2017-01-01T00:00:00ZMaximum Entropy Inferences on the Axion Mass in Models with Axion-Neutrino Interaction
Alves, Alexandre [UNIFESP]; Dias, Alex Gomes; da Silva, Roberto
In this work, we use the maximum entropy principle (MEP) to infer the mass of an axion which interacts to photons and neutrinos in an effective low energy theory. The Shannon entropy function to be maximized is defined in terms of the axion branching ratios. We show that MEP strongly constrains the axion mass taking into account the current experimental bounds on the neutrinos masses. Assuming that the axion is massive enough to decay into all the three neutrinos and that MEP fixes all the free parameters of the model, the inferred axion mass is in the interval 0.1 eV < m(A) < 0.2 eV, which can be tested by forthcoming experiments such as IAXO. However, even in the case where MEP fixes just the axion mass and no other parameter, we found that 0.1 eV < m(A) < 6.3 eV in the DFSZ model with right-handed neutrinos. Moreover, a light axion, allowed to decay to photons and the lightest neutrino only, is determined by MEP as a viable dark matter candidate.
2017-01-01T00:00:00ZCan we discover double Higgs production at the LHC?Alves, Alexandre [UNIFESP]Ghosh, TathagataSinha, Kuverhttps://repositorio.unifesp.br/handle/11600/513762019-08-19T11:49:41Z2017-01-01T00:00:00ZCan we discover double Higgs production at the LHC?
Alves, Alexandre [UNIFESP]; Ghosh, Tathagata; Sinha, Kuver
We explore double Higgs production via gluon fusion in the b (b) over bar gamma gamma channel at the high-luminosity LHC using machine learning tools. We first propose a Bayesian optimization approach to select cuts on kinematic variables, obtaining a 30%-50% increase in the significance compared to current results in the literature. We show that this improvement persists once systematic uncertainties are taken into account. We next use boosted decision trees (BDT) to further discriminate signal and background events. Our analysis shows that a joint optimization of kinematic cuts and BDT hyperparameters results in an appreciable improvement in the significance. Finally, we perform a multivariate analysis of the output scores of the BDT. We find that assuming a very low level of systematics, the techniques proposed here will be able to confirm the production of a pair of standard model Higgs bosons at 5 sigma level with 3 ab(-1) of data. Assuming a more realistic projection of the level of systematics, around 10%, the optimization of cuts to train BDTs combined with a multivariate analysis delivers a respectable significance of 4.6 sigma. Even assuming large systematics of 20%, our analysis predicts a 3.6 sigma significance, which represents at least strong evidence in favor of double Higgs production. We carefully incorporate background contributions coming from light flavor jets or c jets being misidentified as b jets and jets being misidentified as photons in our analysis.
2017-01-01T00:00:00ZBayesian analysis of CCDM modelsJesus, J. F.Valentim, R. [UNIFESP]Andrade-Olivera, F.https://repositorio.unifesp.br/handle/11600/512812019-08-19T11:48:33Z2017-01-01T00:00:00ZBayesian analysis of CCDM models
Jesus, J. F.; Valentim, R. [UNIFESP]; Andrade-Olivera, F.
Creation of Cold Dark Matter (CCDM), in the context of Einstein Field Equations, produces a negative pressure term which can be used to explain the accelerated expansion of the Universe. In this work we tested six different spatially flat models for matter creation using statistical criteria, in light of SNe Ia data: Akaike Information Criterion (AIC), Bayesian Information Criterion (BIC) and Bayesian Evidence (BE). These criteria allow to compare models considering goodness of fit and number of free parameters, penalizing excess of complexity. We find that JO model is slightly favoured over LJO/Lambda CDM model, however, neither of these, nor Gamma = 3 alpha H-0 model can be discarded from the current analysis. Three other scenarios are discarded either because poor fitting or because of the excess of free parameters. A method of increasing Bayesian evidence through reparameterization in order to reducing parameter degeneracy is also developed.
2017-01-01T00:00:00ZMillisecond direct measurement of the magnetocaloric effect of a fe2p-based compound by the mirage effectCugini, F.Porcari, G.Viappiani, C.Caron, L.dos Santos, A. O.Cardoso, L. P.Passamani, E. C.Proveti, J. R. C.Gama, Sergio [UNIFESP]Bruck, E.Solzi, M.https://repositorio.unifesp.br/handle/11600/491962019-01-21T10:29:23Z2016-01-01T00:00:00ZMillisecond direct measurement of the magnetocaloric effect of a fe2p-based compound by the mirage effect
Cugini, F.; Porcari, G.; Viappiani, C.; Caron, L.; dos Santos, A. O.; Cardoso, L. P.; Passamani, E. C.; Proveti, J. R. C.; Gama, Sergio [UNIFESP]; Bruck, E.; Solzi, M.
We present direct measurements of the magnetocaloric effect on a Fe2P-based compound induced by a milliseconds pulsed magnetic field of 1 T to test their possible use in high frequency (up to 100 Hz) thermomagnetic cycles. The reported measurements were performed with an innovative and versatile non-contact set up based on the mirage effect. The adiabatic temperature change of a MnFeP0.45As0.55 sample is presented and compared with measurements performed varying the same magnetic field in a time interval of 1 s and 100 ms. These results demonstrate the absence of kinetic constraints in the first-order phase transition of this sample induced on the milliseconds time scale. The study of the materials' response to millisecond magnetic field pulses represents a fundamental test for the development of more powerful and efficient magnetic refrigerators. (C) 2016 AIP Publishing LLC.
2016-01-01T00:00:00ZOptical properties and antimicrobial effects of silver nanoparticles synthesized by femtosecond laser photoreductionCourrol, Daniella dos SantosLopes, Carla Regina Borges [UNIFESP]Cordeiro, Thiago da SilvaFranzolin, Marcia ReginaVieira Junior, Nilson DiasSarnad, Ricardo ElgulCourrol, Lilia Coronato [UNIFESP]https://repositorio.unifesp.br/handle/11600/459722018-07-26T12:18:28Z2018-01-01T00:00:00ZOptical properties and antimicrobial effects of silver nanoparticles synthesized by femtosecond laser photoreduction
Courrol, Daniella dos Santos; Lopes, Carla Regina Borges [UNIFESP]; Cordeiro, Thiago da Silva; Franzolin, Marcia Regina; Vieira Junior, Nilson Dias; Sarnad, Ricardo Elgul; Courrol, Lilia Coronato [UNIFESP]
Silver nanoparticles exhibit a powerful antimicrobial action showing a pronounced potential to be widely used against drug resistance bacteria. The present work describes the optical properties and antimicrobial effect of silver nanoparticles produced by femtosecond laser photoreduction of AgNO3 in the presence of tryptophan water solution. The advantages of this method are the absence of hazardous chemical reducing agents in the solution, and the versatile dimensional control achieved. The synthesized silver nanoparticles were characterized by absorption and fluorescence spectroscopy and their antibacterial activity were determined by monitoring the cell viability of Escherichia coli. The effects of the silver nanoparticles concentration and laser parameters (exposure time and pulse energy), on the formation of the nanoparticles, and its influence on the bacteria growth inhibition were studied. The prepared silver nanoparticles exhibited suitable antimicrobial properties. The results demonstrated that the nanoparticles concentration plays an important role in their bactericidal efficacy. The increase in the laser energy caused an increase in E. coli growth inhibition. Irradiations with energies around 300 mu j for 60 min presented high antimicrobial activity due to the presence of kynurenine, sub product of tryptophan photolysis. The first-time formation mechanism of tryptophan silver nanoparticles in high optical intensities was also discussed. (C) 2018 Elsevier Ltd. All rights reserved.
2018-01-01T00:00:00ZGreen synthesis of silver nanoparticles with extract of Mimusops coriacea and lightLopes, C. R. B. [UNIFESP]Courrol, Lilia Coronato [UNIFESP]https://repositorio.unifesp.br/handle/11600/459712018-07-26T12:18:27Z2018-01-01T00:00:00ZGreen synthesis of silver nanoparticles with extract of Mimusops coriacea and light
Lopes, C. R. B. [UNIFESP]; Courrol, Lilia Coronato [UNIFESP]
Biological methods of nanoparticle synthesis using plant extracts have been suggested as promising ecofriendly alternative to chemical and physical methods. In this study, spherical silver nanoparticles (AgNP) were synthesized from the aqueous extract of Mimusops coriacea leaves at room temperature. To accelerate the reduction of Ag+ ions was used photoreduction process with Xenon lamp. A presence of resonant surface plasmon band at approximately 415 nm confirms the formation of the nanoparticles. The shape and size of the particles were determined by transmission electron microscopy images indicating sizes from 10 to 30 nm in diameter. Zeta potential indicates good stability. To identify the products for the reduction of Ag+ ions and stability of AgNP, FTIR analysis were performed. An intense reduction in chlorophyll fluorescence was observed after formation of the nanoparticles.
2018-01-01T00:00:00ZDetermination of chicken meat contamination by porphyrin fluorescenceCourrol, Lilia Coronato [UNIFESP]Samad, Ricardo Elgulhttps://repositorio.unifesp.br/handle/11600/459702018-07-26T12:18:27Z2018-01-01T00:00:00ZDetermination of chicken meat contamination by porphyrin fluorescence
Courrol, Lilia Coronato [UNIFESP]; Samad, Ricardo Elgul
Meat quality is normally defined by a combination of factors such as visual appearance, smell, firmness, succulence, tenderness, and flavor. Contamination of poultry meat with pathogens remains an important public health issue since it can cause illnesses due to negligence in handling, cooking or post-cooking storage. Conventionally, meat quality tests are based on visual evaluation or chemical analysis, which have the disadvantages of being subjective and time-consuming. To improve the biological contamination detection accuracy and productivity, the evaluation of porphyrin contents in meat by fluorescence spectroscopy is proposed, considering that most microorganisms and animal cells excrete porphyrins. For this purpose, chicken meat was cut into small pieces and separated in three groups: a control group where the meat was conserved under refrigeration, and two experimental groups in which the pieces were kept for 24 and 30 h at room temperature. Porphyrin was extracted from the meat samples and the fluorescence was measured in the range 550-750 nm, under excitation around 400 nm. The fluorescence lifetime was also studied. To ensure porphyrin synthesis, a concentration of 9.3 mM of delta-Aminolevulinic acid (ALA) was added to each sample, 2 h before porphyrin extraction. The results show that, in meat kept at room temperature and incubated with ALA, the porphyrin fluorescence increased, and a short-lived component was enhanced due to the action of microorganisms, indicating a potential new method to test meat quality.
2018-01-01T00:00:00ZConfocal and atomic force microscopies of color centers produced by ultrashort laser irradiation in LiF crystalsCourrol, Lilia Coronato [UNIFESP]Martinez, OscarSamad, Ricardo ElgulGomes, LaercioRanieri, Izilda MarciaBaldochi, Sonia LiciaFreitas, Anderson Zanardi deVieira Junior, Nilson DiasWetter, N. U.Frejlich, J.https://repositorio.unifesp.br/handle/11600/455282018-06-18T11:54:41Z2008-01-01T00:00:00ZConfocal and atomic force microscopies of color centers produced by ultrashort laser irradiation in LiF crystals
Courrol, Lilia Coronato [UNIFESP]; Martinez, Oscar; Samad, Ricardo Elgul; Gomes, Laercio; Ranieri, Izilda Marcia; Baldochi, Sonia Licia; Freitas, Anderson Zanardi de; Vieira Junior, Nilson Dias; Wetter, N. U.; Frejlich, J.
We report properties of the spatial and spectral distribution of color centers produced in LiF single crystals by ultrashort high intensity laser pulses (60 fs, 10 GW) using confocal spectral microscopy and atomic force microscopy. We could identify a large amount of F centers that gave rise to aggregates such as F-2, F-4, F-2(+) and F-3(+) distributed in cracked shape brownish areas. We have taken a 3D image using confocal microscopy of the sample (luminescent image) and no difference is observed in the different planes. The atomic force microscopy image clearly shows the presence of defects on the modified surface. The formation of micrometer or sub-micrometer voids, filaments and void strings was observed and related to filamentation process.
2008-01-01T00:00:00ZElastic scattering and total reaction cross section of He-6+Sn-120Faria, P. N. deLichtenthaler, R.Pires, K. C. C.Moro, A. M.Lepine-Szily, A.Guimaraes, V.Mendes, D. R.Arazi, A.Rodriguez-Gallardo, M.Barioni, AdrianaMorcelle, V.Morais, M. C.Camargo, O.Nunez, J. AlcantaraAssuncao, Marlete [UNIFESP]https://repositorio.unifesp.br/handle/11600/324492018-08-16T13:15:34Z2010-04-01T00:00:00ZElastic scattering and total reaction cross section of He-6+Sn-120
Faria, P. N. de; Lichtenthaler, R.; Pires, K. C. C.; Moro, A. M.; Lepine-Szily, A.; Guimaraes, V.; Mendes, D. R.; Arazi, A.; Rodriguez-Gallardo, M.; Barioni, Adriana; Morcelle, V.; Morais, M. C.; Camargo, O.; Nunez, J. Alcantara; Assuncao, Marlete [UNIFESP]
The elastic scattering of He-6 on Sn-120 has been measured at four energies above the Coulomb barrier using the He-6 beam produced at the RIBRAS (Radioactive Ion Beams in Brasil) facility. the elastic angular distributions have been analyzed with the optical model and three- and four-body continuum-discretized coupled-channels calculations. the total reaction cross sections have been derived and compared with other systems of similar masses.
2010-04-01T00:00:00ZElastic scattering and total reaction cross sections for the Li-8+C-12 systemBarioni, AdrianaGuimaraes, V.Lepine-Szily, A.Lichtenthaeler, R.Mendes, D. R.Crema, E.Pires, K. C. C.Morais, M. C.Morcelle, V.Faria, P. N. deCondori, R. P.Moro, A. M.Monteiro, D. S.Shorto, J. M. B.Lubian, J.Assuncao, Marlete [UNIFESP]https://repositorio.unifesp.br/handle/11600/317992018-08-16T13:17:06Z2009-09-01T00:00:00ZElastic scattering and total reaction cross sections for the Li-8+C-12 system
Barioni, Adriana; Guimaraes, V.; Lepine-Szily, A.; Lichtenthaeler, R.; Mendes, D. R.; Crema, E.; Pires, K. C. C.; Morais, M. C.; Morcelle, V.; Faria, P. N. de; Condori, R. P.; Moro, A. M.; Monteiro, D. S.; Shorto, J. M. B.; Lubian, J.; Assuncao, Marlete [UNIFESP]
The elastic-scattering angular distribution for Li-8 on C-12 has been measured at E-LAB = 23.9 MeV with Li-8 radioactive nuclear beam produced by the Radioactive Ion Beams in Brazil facility. This angular distribution was analyzed in terms of optical-model with Woods-Saxon and double-folding São Paulo potential. the roles of the breakup and inelastic channels were also investigated with cluster folding and deformed potentials, respectively, through coupled-channels calculations. the angular distribution for the proton-transfer C-12(Li-8, Be-9)B-11 reaction was also measured at the same energy. the spectroscopic factor for the < Be-9|Li-8 + p > bound system was obtained and compared with shell-model calculations and with other experimental values. Total reaction cross sections for the present system were also extracted from the elastic-scattering analysis. A systematic of the reduced reaction cross sections obtained from the present and published data on Li-6,Li-7,Li-8 isotopes on C-12 was performed as a function of energy.
2009-09-01T00:00:00ZNeutron transfer reactions induced by Li-8 on Be-9Guimaraes, V.Lichtenthaler, R.Camargo, O.Barioni, AdrianaAssuncao, Marlete [UNIFESP]Kolata, J. J.Amro, H.Becchetti, F. D.Jiang, HaoAguilera, E. F.Lizcano, D.Martines-Quiroz, E.Garcia, H.https://repositorio.unifesp.br/handle/11600/297322018-08-16T13:23:58Z2007-05-01T00:00:00ZNeutron transfer reactions induced by Li-8 on Be-9
Guimaraes, V.; Lichtenthaler, R.; Camargo, O.; Barioni, Adriana; Assuncao, Marlete [UNIFESP]; Kolata, J. J.; Amro, H.; Becchetti, F. D.; Jiang, Hao; Aguilera, E. F.; Lizcano, D.; Martines-Quiroz, E.; Garcia, H.
Angular distributions for the elastic scattering of Li-8 on Be-9 and the neutron transfer reactions Be-9(Li-8,Li-7)Be-10 and Be-9(Li-8,Li-9)Be-8 were measured with a 27 MeV Li-8 radioactive nuclear beam. Spectr- oscopic factors for Li-8 circle times n= Li-9 and Li-7 circle times n= Li-8 bound systems were obtained from the comparison between the experimental differential cross section and finite-range distorted-wave Born approximation calculations with the code FRESCO. the spectroscopic factors obtained were compared to shell model calculations and to other experimental values from (d,p) reactions. Using the present values for the spectroscopic factor, cross sections for the direct neutron-capture reactions Li-7(n,gamma)Li-8 and Li-8(n,gamma)Li-9 were calculated in the framework of a potential model.
2007-05-01T00:00:00Z