<span data-sheets-value="{"1":2,"2":"O Encontro de História da Arte é um evento de caráter anual, promovido pelo corpo discente do Programa de Pós-Graduação em História da Unicamp e com sede no Instituto de Filosofia e Ciências Humanas. Desde 2004, tem por objetivo reunir pesquisas de todo o Brasil sobre história da arte e da cultura, sem distinções de titulação."}" data-sheets-userformat="{"2":769,"3":{"1":0},"11":4,"12":0}">Descrição: Physicae Proceedings é voltado para eventos da área de física geridos por alunos de Pós-Graduação do IFGW. <span data-sheets-value="{"1":2,"2":"O Encontro de História da Arte é um evento de caráter anual, promovido pelo corpo discente do Programa de Pós-Graduação em História da Unicamp e com sede no Instituto de Filosofia e Ciências Humanas. Desde 2004, tem por objetivo reunir pesquisas de todo o Brasil sobre história da arte e da cultura, sem distinções de titulação."}" data-sheets-userformat="{"2":769,"3":{"1":0},"11":4,"12":0}"> Ano de criação: 2010 Área do Conhecimento: Física ISSN: 2236-7535 Título abreviado: Phys. Proc. Contato: apgf@ifi.unicamp.br Unidade: APGF/IFGW/UNICAMP
Self-organization of surfactant molecules on immersed gold substrates
The adsorption of surfactants on solid substrates is subject of both fundamental and applied interests. Many nano-sized systems used in drug delivery formulations in pharmacological sciences are constituted by surfactants alkyl ether sulfates, CnSO4, and polyoxyethylene alkyl ethers, CnEm. The aim of this work was to study the interaction of dilute solutions (below the critical micelle concentration, CMC) of different ionic (the alkyl ether sulfates C10SO4, C12SO4, C14SO4 and C18SO4) and nonionic surfactants (the alkyl ethers C10E8, C12E8, C14E8, C16E8 and C18E8) with the surface of a polycrystalline gold electrode of a electrochemical quartz crystal microbalance (EQCM). The gold electrode surfaces, after the film adsorption, were characterized with the Atomic Force Microscope (AFM) and potentiostatic measurements.
Neutrino mass from different SeeSaw mechanisms
The flavor oscillation phenomenon detected in solar and atmospheric neutrinos proved that neutrinos have mass. However, the origin and the neutrino mass values are still unknown, since the oscillations parameters are only the difference of the squared mass and the mixing angle between the different eigenstates. From theoretical point of view the seesaw mechanism is the preferred model to explain neutrinos mass. In order to generate the left-handed neutrino mass, the type I seesaw mechanism extends the Standard Model content including right-handed neutrinos as SU (2) ? U (1) singlet with Majorana mass term M. After the mass matrix diagonalization, the type I seesaw mechanism provides the following expression suppressed by the high-scale M in its denominator: m? ? v^2ew /M , where vew is a energy scale parameter at the electroweak range. Low energy phenomelogy requires vew ? 246GeV . Due to this fact, we see that neutrinos with mass at eV scale are obtained with M ? 10^15 GeV . This higher energy makes hopeless any kind of experimental test. With the purpose of realize the seesaw mechanism at TeV scale, we study the Triple Seesaw Mechanism, presenting, in this way, a mechanism with great potential of being probed at LHC. The minimum Higgs sector required by this mechanism is composed by the standard Higgs doublet plus another Higgs doublet and one Higgs singlet. Due to this extended Higgs sector, the expression for the neutrino masses in this mechanism get suppressed by the high-scale M^3 in its denominator. We are reviewing triple seesaw mechanism in a scenario where the heavy right-handed neutrinos mass is close to (1 ? 10)T eV . Finally, we extend this work considering the mass term ?1 of the non standard Higgs of same magnitude of the high-scale M of the right-handed neutrinos, but the trilinear term in the potential is not restricted which gives us more liberty to arrange the neutrino mass. In conclusion, with this modification, we obtain an expression for m? which get suppressed by M^5.
Local and global magnetic properties of reduced dimensions systems
Reduced dimensions systems present many potential technological applications. There is great interest in the development of small scale devices as well as in the control and manipulation at the nanoscale and in study of finite size on physical properties. Ag:R and NaYF4 :Gd NPs were prepared by chemical method. We observed a typical Lorentzian line-shape ESR lines for all studied dopants (R = Er, Yb e Mn). The g-factor found for Er3+ , Yb3+ e Mn2+ in the nanoparticles is very close to g-value found in ground-states of these ions in insulating cubic systems, in contrast that what was found in metals, where it is observed a g-shift for the metallic system. Furthermore, it was not possible to observe the Korringa relaxation for the ESR lines of Er3+ , Yb3+ e Mn2+ in the NPs system typically observed in metals. Therefore, the results suggest that the exchange interaction (Jfs) between localized magnetic moments (ML) and conduction electrons (c-e) is absent in Ag:R NPs, indicating that the nature of this interaction needs to be reexamined at the nanoscale range. For NaYF4 :Gd NPs, the particle control size was obtained by the amount of rps = precursor/surfactant. There was no evidence of Gd clusters in our results and we found the same characteristics observed in the bulk system: three resonance lines, with the controversies origins. It is still unknown the source of crystalline field of cubic symmetry with tetragonal combinations or orthorhombic or even Gd3+ sites with lower symmetries.Reduced dimensions systems present many potential technological applications. There is great interest in the development of small scale devices as well as in the control and manipulation at the nanoscale and in study of finite size on physical properties.
Analyzing the EPR spectra of a selfstanding conducting polymer film we noticed the asymmetry of the first derivative of the EPR line, suggesting that we should use a Dysonian line. This Dysonian line can be represented by a combination of absorption and dispersion Lorentzian lines. However we noticed that adding a small Gaussian line would improve the fitting. Hence, due to the skin depth, we introduced numerically a dispersion contribution to this absorption Gaussian line according to G. E. Pake and E. M. Purcell (Phys. Rev. 74, 1184–1188 (1948)). To our knowledge, this is the first time that this dispersive contribution of the Gaussian line has been introduced in the analysis of the EPR spectrum.
Espectroscopia Raman em Ba1?x Lax Ti0,5 Mn0,5 O3
A perovskita LaMnO3 apresenta antiferromagnetismo abaixo da temperatura de Neel TN[1], já na perovskita BaTiO3 o deslocamento dos íons de Ti de sua posição central no octaedro TiO6 faz surgir um momento de dipolo elétrico na célula unitária, favorecendo o aparecimento de domínios ferroelétricos[2]. A síntese de materiais que possuam características magnéticas e elétricas pode gerar interessantes protótipos de dispositivos de armazenamento de dados que sejam sensíveis às duas propriedades e o sistema Ba1?x Lax Ti0,5 Mn0,5 O3 nos permite verificar se tal dispositivo é realizável. Neste trabalho apresentamos espectros Raman no composto Ba1?x Lax Ti0,5 Mn0,5 O3 para x = 0.0, 0.2, 0.3, 0.4 e 0.5 onde foi variada a temperatura de medida para cada amostra de 30 a 300K. Uma análise de Grupo Fator para o composto em x=0 (grupo espacial ) mostra que são permitidos 16 modos Raman ativos e através da Fig. 1, verificamos que existe um grande número de picos, que pode inclusive exceder a previsão de 16 modos para este material. Alternativamente, alguns modos de vibração podem apresentar "ombros" devido a flutuações na composição Ti/Mn ao longo da amostra, formando a impressão de vários picos sobrepostos. Além disso, os espectros da Fig. 1 mostram uma clara mudança na linha do espectro conforme é adicionado La. Para x=0, um grande número de picos é observado, enquanto que para x ? 0.4 um espectro com poucos picos largos aparece. Para x=0.2 e x=0.3 parece haver uma sobreposição entre os picos relativamente finos observados para x=0 com os picos mais largos observados para x>=0.4. Ocorre um claro aumento de simetria com a adição de La que é observado na diminuição de picos entre x = 0.0 e x = 0.5. Uma possível explicação para este comportamento seria uma transição de fase estrutural induzida pela incorporação de La, com possível coexistência de fases para x=0.2 e x=0.3.
Dynamical properties of the Fermi-Ulam model with external perturbation of Van der Pool type
In this work we consider the dynamics of a classical particle of mass m confined within an one-dimensional time dependent billiard. We assume that the time perturbation of the boundary is given by a nonlinear Van der Pool oscillator. The particle is confined to move between the two rigid walls, one of them fixed at a distance L from the first that fluctuates according to the Van der Pol oscillator. We construct the phase space and explore the dynamic properties of the system. The Van der Pol oscillator is a modification of the harmonic oscillator where a dissipative and nonlinear term is introduced. The equation describing the oscillator is M d^2x/dt^2 + b(x^2 ? x0^2 )dx/dt + kx = 0 where b is a dissipative term, M is the mass, and k is the Hook constant.
Phase diagram of the Ba(Fe1?x Cox )2 As2 single crystal grown from In flux
The interplay between magnetism and superconductivity in the iron arsenide superconductors have generated great interest in past years. Here we present the growth and characterization of Ba(Fe1?x Cox )2 As2 single crystals grown from In-rich flux, which represents an alternative to the conventional self-flux method. This method does not require excess Fe or As, which the latter is a danger to the grower. The crystals have dimensions up to 2.0 × 2.0 × 0.05 mm3 . They were characterized by electrical resistivity, magnetic susceptibility, specific heat and X-ray diffraction measurements. The determination of the transition temperatures allowed the construction of the phase diagram for this series. The obtained phase diagram is confronted with the ones in literature.
We study the behavior of two weakly coupled quantum systems, described by a separable density operator. One of them is a single oscillator, representing a microscopic system, while the other is a set of oscillators, which perform the role of a reservoir in thermal equilibrium. From the Liouville-Von Neumann equation for the reduced density operator, we devise the master equation that governs the evolution of the microscopic system, incorporating the effects of temperature via Thermofield Dynamics formalism and suitably redefining the vacuum of the macroscopic system. As applications, we study an oscillator interacting with a set of boson oscillators at finite temperature, usually employed in quantum mechanics to describe a Brownian particle; and investigate the behavior of an oscillator in the presence of a heat bath consisting of a set of fermion oscillators.
Physical properties of Sb2 O3 - P2 O5 glasses
Some physical properties of a Sb2 O3 -P2 O5 glass were analyzed. A glass with composition (mol%) 75Sb2 O3 25P2 O5 were melted in an electrical furnace and in glassy carbon crucible at 1000 . Samples were cutted, lapped and polished with cerium oxide and using ethylene glycol as polishing fluid, since the glass presents some hygroscopicity. Using the Archimedes principle and ethylene glycol again as immersion fluid, the density of the glass was determined to be ?= (4,774±0,001) g/cm^3. The pulse-echo method was applied to determine the longitudinal and transversal ultrasonic velocities. These values enable the calculation of the Young modulus, E, and the Poisson coefficient, ?: E = (39±2) GPa and ? = 0,22±0,01. The experimental value of the hardness was obtained from measurements of the Vickers impression diagonals, d, produced by applying loads, P , up to 500 g: H = (2,31±0,04) GPa. Dilatometric measurements indicate that the glass transition temperature, Tg, is about 300 , and the dilatometric softening temperature, Td, is 330 . The coefficient of thermal expansion, ?, between 150 and 270 is 17.3 x 10?6 °?1 . Once the glass is transparent, the refractive index was obtained by using an optical microscope. This values is roughly given: n = (1,96±0,08). Therefore one can conclude that, although the low values of the Young modulus and hardness, the high value of the refractive index demonstrates that this glass can present interesting optical applications.
Finite chaotic environment as a thermal reservoir
We study the flow of energy between a harmonic oscillator (HO) and an external environment consisting of N two-degrees-of-freedom nonlinear oscillators, ranging from integrable to chaotic according to a control parameter. The coupling between the HO and the environment is bilinear in the coordinates and scales with system size as 1/Sqrt(N) . We study the conditions for energy dissipation and thermalization as a function of N and of the dynamical regime of the nonlinear oscillators. The study is classical and based on a single realization of the dynamics, as opposed to ensemble averages over many realizations. We find that dissipation occurs in the chaotic regime for fairly small values of N, leading to the thermalization of the HO and the environment in a Boltzmann distribution of energies for a well-defined temperature. We develop a simple analytical treatment, based on the linear response theory, that justifies the coupling scaling and reproduces the numerical simulations when the environment is in the chaotic regime.
Hydrostatic pressure and temperature dependence of the band structure in a 1-D semiconductor phtonic crystal
The band structure of a one-dimensional photonic superlattice composed of alternate layers of air and GaAs characterized by different refractive indexes have been theoretically investigated using a transfer matrix technique. In addition to the well known existence of the band gaps, we show that the band gaps depends on the width relationship between the layers materials, also, we have found that the temperature dependence of the photonic band structure is negligible, however its main changes are due to the variations of the width and the dielectric constant of the layers of GaAs, caused by the applied hydrostatic pressure.
A flat, single layer of graphite known as graphene has become the focus of studies due to its exceptional properties and fascinating applications. Large scale graphene layers for a possible application can be grown epitaxially on SiC by Si sublimation [1]. Even before the interest in graphene, the surface of SiC was already extensively studied [2],[3]. It exhibits a large variety of surface reconstructions and these reconstructions are very dependent of sample preparation and orientation (0001) or (000-1). In this study, we show a investigation of the structural properties of graphene layers on SiC (0001) by photoelectron diffraction (XPD). The surfaces were prepared by heating the 1x1 surface to temperatures of about 1150 in high ultra vacuum and the various reconstructions were monitored by Low Energy Electron Diffraction (LEED) and X-Ray Photoelectron Spectroscopy (XPS). In particular for the Si terminated surface, that is SiC(0001), the interface between graphene and SiC is characterized by the so-called (6Sqrt(3) × 6Sqrt(3))R30? reconstruction (buffer layer). The interpretation of this reconstruction, which is the initial stage of graphitization, has lead to controversy in the literature [2]. We will further discuss the buffer layer structure in terms of the XPD results. The XPD experiments were performed at SGM beam line at LNLS using photons with 450 eV probing the Si2p and C1s core level. The C1s signal was separate in to contributions from volume and surface and compares the experimental results with photoelectron multiple scattering calculations performed with the MSCD package [4].
Noise spectroscopy in cold Rubidium atoms in EIT configuration
Using noise spectroscopy, we studied the correlations between two light beams with opposite circular polarization, coupling the transition F=2 -> F’=2 in ? EIT configuration, with cold atoms of Rubidium-85. In the spectrum of correlation we observed the transition from correlation to anti-correlation, off-resonance, when raising the potency of the beams.This transition is a consequence of the competition between four-wave mixing, which is responsible for the correlation regime, and the Stark effect that produces anti-correlation in the beams.In the spectra of mean signal of intensity and correlation, we observed that the EIT peak is free of potency broadening, which makes possible that the measure of coherence time be more precise in the condition of EIT. Using a EIT’s model for a system in ? configuration, we observed that the theoretical correlation spectra are in good accordance with the experimental data, considering the degenerescence of the hyperfine levels. Besides that, the model predicts the non-broadening of the correlation peak, showing the correlation as a characterization property more accurated than the mean signal of intensity.
Transfer of two qubits states using coupled cavities in off-resonance systems
In this work we studied a system consisting of a pair of two-level trapped ions in coupled optics cavities, where we analyze the transfer of states of two qubits from the degrees of freedom (of movement and of internal states) of one ion to another. This system was studied near the blue side band frequency with a small gap. With analytical results obtained was possible to calculate the fidelity of transfer of entangled qubits.
Effect of heat treatment on the structural and magnetic properties of the system Fe56.25 Al43.75 prepared by mechanical alloying
The study of the Fe56.25 Al43.75 system prepared by Mechanical Alloying (MA), using elementary powders, at different times (12, 24, 48, 72 and 96 hours), named MA0 samples, showed that the alloy is consolidated at 48 hours. Taking the sample for this time it was compacted at 1 ton, encapsulated in an Ar filled quartz tube and a heat treatment at 700?C for 9 days was performed. Then the thermally treated samples, were mechanically alloyed (1, 4, 8, 12, 24 and 48 hours), named MA1 samples. For all samples, a magnetic and structural properties study was conducted by Mössbauer Spectrometry (MS) and X-Ray Diffraction (XRD). XRD results for MA0 samples allow us to consider the system as a nanostructured one who presents a single disordered BCC phase where the lattice parameter is approximately constant (2.900 ) and a decrease of the crystallite size with increasing milling time was found. For the thermally treated sample XRD results show that they exhibit some degree of ordering. The XRD patterns allow us to identify the following phases, FeAl, Fe3Al, FeO and ?-Fe which tend to disappear with milling time. Additionally an Fe-Al metallurgical phase was proposed. MS results for the MA0 samples a ferromagnetic phase was found. An increase in the mean hyperfine field (MHF) was found resulting from the MA induced structural disorder. From MS of MA1 samples it was found that for times (0, 1, 4, 8 and 12 hours), there is a tendency to ordering and the presence of a doublet with QS = 0.48 mm s-1 and ?exp = 0.50 mm s-1, that we associate to the FeAl phase, needs to be included. Likewise for times (24 and 48 hours), we obtained a doublet with QS = 0.95 mm s-1 and ?exp = 0.30 mm s-1, associated with the FeO phase (wüstite), maybe due to an oxidation promoted by a leak in the seal of the jars.
Relaxor behavior in multiferroic BiMn2 O5
In polycrystalline BiMn2 O5 a broad thermal stimulated depolarization current (TSDC) curve has been observed in the range from 10 K to 300 K and the pyroelectric coefficient determined. In magnetic susceptibility measurements reported in the literature, features appearing in the pyroelectric coefficient could also be identified for the same temperatures, suggesting a connection between electric and magnetic data above the Néel temperature. A detailed study of the dielectric constant from 240 K to 700 K for an extended range of frequencies revealed a broad maximum at low frequencies, characteristic of relaxor ferroelectrics, following Vogel-Fulcher relation. A freezing temperature of the polar nanoregions Tf = 512 K has been determined. This high temperature ferroelectric behavior is attributed to the Bi3+ in the distorted BiO8 cage.
Thermal stimulated depolarization current
Structural and hyperfine comparative study of ball-milled and arc-melted Fe50 Cr50 alloys
In this work we make a structural and hyperfine comparative study of the Fe50 Cr50 stoichiometric alloy obtained for two different techniques, mechanical alloying and arc-melting. Both alloys were heated to 650 ? C for 7 days, quenched into ice water and then mechanically alloyed for different milling times. Before heat treatment the two alloys exhibit Fe-Cr BCC structure and ferromagnetic behavior similar, after treatment, in the alloy obtained by mechanical alloying, the BCC structure is completely transformed into the ordered structure ? Fe-Cr, whereas that in the alloy obtained by melted this transformation is partial. The mechanical alloying realized in the last stage affect notoriously the structure ? Fe-Cr, for 2 hours of milling the structure is completely disordered, subsequently transformed into BCC Fe-Cr phase, and disappears at 16 hours of milling.
In these work we study the effects resulting from the action of electron beams (similar to the solar wind, 650-1500 eV) reaching methanol ice, and highly energized particles (58Ni11+, 46 MeV, similar to cosmic rays), reaching formic acid ice, so we can analyze the chemical evolution of these ices, and obtain certain parameter, once some organic molecules found in interstellar medium, such as methanol and formic acid, are of great interest for understanding the mechanisms of origin of life, since they are important precursors of prebiotic species, like glycine, the simplest aminoacid. Methanol and formic acid are found abundantly in many astrophysical environments, such as comets, protostars, chondritic meteorites and regions associated with formation of stars. These environments are often subjected to the action of ionizing particles and photons. Thus, the study of photodissociation/ photofragmentation processes, induced by impact of electrons, ions or photons, and consequent formation of more complex molecules, are very important for understanding the chemical evolution of these environments. The experiments were conducted in two different laboratories: Laboratory of Surface Chemistry of Federal University of Rio de Janeiro (Laquis / UFRJ) for electron’s beam in methanol ice, and the Grand Accélérateur National d’Ions Lourds (GANIL – France), for 58Ni11+ beam in formic acid ice. The spectra of desorbed ions were obtained from the technique of time-of-flight mass spectrometry (TOF – MS) for methanol, and Fourier Transform Infrared Spectrometry (FTIR), for formic acid. The magnitudes analyzed were: desorption yield (for methanol ice), and cross-sections of the destruction and formation of molecules in the ice of formic acid, as well as desorption yields and half life of this molecule in Earth’s atmosphere.
Semiclassical initial value representation with complex trajectories
Semiclassical time-dependent solutions to the Schroedinger equation can be obtained by use of integral formulas known as initial value representations (IVRs). Over the last few decades IVR formulas have established a sucessful reputation, most notably in the field of physical chemistry, for it is often found that the quantum behavior of molecular systems is very well approximated by semiclassical wavefunctions. The IVR input consists in a swarm of independent classical trajectories, each of which obeys the dynamics dictated by the system’s unquantized Hamiltonian. In a recent work [Aguiar et al, Chem. Phys. 370 (2010)] an IVR expression based on complex classical trajectories was formulated. The complex nature of the classical trajectories in this particular formula is a consequence of employing minimum uncertainty wavepackets (coherent states) to represent the time evolution operator upon which the formula is constructed. Here, an improved and simpler version of this complex IVR formula is presented. In order to test its accuracy, we apply it to a simple model system.
Influence of membrane composition on its flexibility
Lamellar phases and vesicles composed of lipids have been used as model systems to investigate biological process related to cell membrane as well as promising carriers for drugs and gene therapy. The composition of the membrane determines its three dimensional shape and its properties such as rigidity and compressibility which play an important role on membrane fusion, protein adhesion, interactions between proteins, etc. We present systematic study of a lamellar system composed mainly of lecithin which is a biocompatible phospholipid and simulsol, which is a mixture of fatty acids and acts as a co-surfactant introducing flexibility to the membrane. Using X ray scattering we determine the lamellar periodicity as a function of the hydration for two different formulations of the membrane; with 70% and 30% mass fraction of simusol, respectively. The X ray spectra are fitted using a simple model that allows us to determine the lamellar periodicity and the Caillé parameter [1, 2]. The ideal swellinglaw relating the membrane volume fraction (?m ) to the lamellar periodicity (D) is given by ?m =?m /D, where ?m is the thickness membrane, however, when steric interactions are dominant with respect to electrostatic and van der Waals interactions, deviations from this behavior are expected [3]. We present experimental data illustrating the swelling behavior for the two membrane compositions and the respective behavior of the Caillé parameter, which is related to the bending rigidity (k) and compressibility modulus of the membrane (B).
Emergence of criticality in different topologies of networks of map-based neurons
KTz model is a three-dimensional map representing the action potential, a recovery and a slow variable, and exhibits the usual excitable cells behaviors (fast and regular spiking, bursting, etc). When we connect KTz’s units in different topologies with a probabilistic two-dimensional Chemical Synapse Map (CSM) we obtain spike avalanches, which is a number of connected neurons spiking one after another. The critical systems show a power law distribution of avalanches, and this is also a signature of Self-Organized Criticality (SOC). In vitro systems have shown neuronal avalanches. Comparisons between LFP recordings in monkeys performing a short term memory task and three subsampled SOC models are available in the literature, as well as in vivo data from rats and a cellular automaton model. These results are promising, and show close connection between critical models and neuronal activity. We simulate KTz neurons connected through CSM on different types of networks (square, scale-free, small world) and our preliminary results show criticality in the square lattice. Random topologies are under check, and they may be of close interest of the medical community, since they can be related to the development of some neural diseases.
Nonextensive statistics for time evolution of interacting particles
A system of interacting particles under a overdamped motion is known to be a model able to describe flux front penetration in disordered type-II superconductors. Was shown recently, that a coarse-grained representation of this system leads to a nonlinear Fokker-Planck formalism, corresponding to a Tsallis statistic with q=0, that is appropriate to describe the stationary state. In this work, we repeat same approach making a molecular dynamic simulation confirming that the temporal evolution of this system is also described by the same theory. We present the probability distribution for particle velocity and particle position, that is in agreement with the analytical solution of nonlinear Fokker-Planck equation related. We found that horizontal distribution for velocity and position follow equal entropic index q=0, for all time. For vertical velocity distribution, a sequence of q-Gaussian under evolution are found until the equilibrium state.
Quantum fluctuations sampling by means of classical molecular dynamics
We study a new method devised to sample the canonical ensemble [H. Dammak et al., Phys. Rev. Lett. 103, 190601 (2009)], which includes quantum fluctuations by means of classical Molecular Dynamics. This method is based on classical stochastic thermostats, except that it uses colored noise, instead of a white one. We show that, although we have excelent results for the harmonic oscillator case, problems arise while studying anharmonic potentials, in which the method sample distributions that are fundamentally incorrect. A suggestion about where is the problem is given, but no solutions until the moment.
Generation of bipartite bound entanglement
We introduce a class of entangled bipartite states that are positive under partial transposition operation,i.e., PPT bound entangled states. These states are based on realistical preparation procedures in optical systems, being thus a feasible option to generate and observe bipartite bound entanglement in high precision experiments. The method employed to detect entanglement has the advantages of being simple, analitical and independent of the range criterion. We also link PPT property of one-mode states that pass a beam-splitter to Hankel operator theory and related moment problems.
We propose a new technique for authentication of oil paintings, using a scanning SQUID or fluxgate technique to measure its magnetic field. The paintings are pre-magnetized in an homogeneous field of 100 G. It was observed that the response depends on the ferromagnetic properties of each paint independent of its colour. This shows that a magnetic image could be used as a magnetic signature for authentication purposes.
Ultrashort x-ray pulses production through amplified femtosecond lasers
The study of dynamics of ultra-fast phenomena is an interesting field of research, which has received a lot of attention from the scientific community recently due to the development of new technology that reaches the time resolution necessary for measuring this kind of phenomena. Several experiments have been made in the last years using pump and probe technics in order to observe the dynamics of materials with different scattering techniques, yet, most of these experiments are based on synchrotron sources and therefore are limited to a temporal resolution typical of those facilities - order of 100ps. The aim of this project is to produce a tabletop femtosecond x-ray source with sub-picosecond temporal resolution and high autonomy. The x-ray production occurs through the focalization of a femtosecond infra-red laser beam over a metal target, the interaction of the laser with the target results in plasma formation for a short period of time (basically the pulse duration of the the laser), which results K-alpha emission - Bremmsstrahlung. The complete setup includes optics for the laser focusing, an automated self-renewing target and several other components to ensure high autonomy and stability. The source will be able to perform pump and probe experiments using as a pump the laser source with the addition of delay lines or other pumping components such as electric or magnetic field pulse generators and using synchronization electronics. This source is currently being built at the X-ray Applied Crystallography Laboratory (LCARX) of the Physics Institute Gleb Wataghin at UNICAMP.
Neutron fluence measurements for Boron Neutron Capture Therapy (BNCT)
The Boron Neutron Capture Therapy (BNCT) is an internal radiotherapy, in which 10 B compounds, selectively delivered to tumor cells, capture neutrons from an external source, emitting an particle and a recoil 7 Li nucleus. These two particles present high LET and their combined range (< 10 m) is in the magnitude of the cell radius, ideally affecting only the tumor cells, sparing healthy tissue. However, in spite of the high cross-section for the reaction 10 B(n,)7 Li, 3,800 barn, recoil of nitrogen, oxygen, carbon and mainly hydrogen, present in healthy tissue, after fast neutron recoil, give rise to a low LET component for the dose that has to be taken into account for treatment purposes. Other fast neutron reactions ((n,p), (n,) and (n,d)) with nitrogen, oxygen and carbon, may also become important for higher neutron energies.In this way, accurate determination of neutron fluencies, preferably separating thermal and epithermal components, are desirable for treatment planning as well as for evaluating studies of biodistribution in candidate boron-carrier drugs. In this presentation, the important aspects for the BNCT application are reviewed and a technique for measuring 10 B(n,)7 Li reaction rate and the fast neutron component, based on etched-track detector and boron thin films, is presented and discussed.
Astrophysics of the ultra high energy cosmic rays detected by the Pierre Auger Observatory
This seminar will focus on the physics and astrophysics of ultra high energy cosmic rays (E > 1 EeV), with emphasis on the results reported by the Pierre Auger Collaboration and the interpretation of the experimental data. We will discuss the intriguing and apparent contradiction between the correlation of arrival directions of cosmic rays with astrophysical objects and observables related to the chemical composition of the primary particles. Neutrinos and photons of ultra high energy will also be discussed.
To the chemist, all matter is composed of protons, neutrons, and electrons. But the first two are not "elementary" – they are composite structures made out of quarks. And there are many other particles, beyond the classical three. What are the "true" elementary particles, how do they interact, and why aren’t we aware of them (except for the electron) in everyday life?
Raman spectroscopy of carbon nanostructures
The carbon nanostructure was always in our life. It is rather surprising to think that graphene (a graphite sheet) has been considered today as a material that will replace silicon technology in our future. This lecture is an exercise done for the understanding of how scientific advances always make us go beyond. The advances are analyzed from the point of view of Raman spectroscopy. How come that a simple physical process, such as inelastic scattering of light, gives us the tools for the development of nanotechnology? - which means no more than the mastery by man of processes often conducted in nature.