Physics

An integrated campaign for monitoring of thunderstorms in São Bernardo do Campo region, occurred at FEI from November 2004 to March 2005. The aim of this campaign is study the electrical-meteorological behavior in a high lightning activity region. The local electric field, the lightning activity and the general weather conditions were being monitored. This monitoring identified the convective cells, their life stages and activity of total and CG lightning flashes. Eight events were monitored by local electric field, video cameras and lightning detection simultaneously. These events showed strong wind and high rainfall accumulation and caused several local floods in São Bernado do Campo and São Paulo City. The most of storms presented variation of local electric field exceeding to 16kV/m for about 4 hours. Some transients of IC and CG lightning were recorded been identified visually by video camera. Rate of total flashes, 5 per min. -1 , suggest occurrence of ordinary thunderstorms. About 29.5 thousands of CG lightning flashes were analyzed. These storms were predominantly negative, about 94%, and presented average peak current of above 25 kA common for this region.

The interaction between a very thin macroscopic solenoid, and a single magnetic particle precessing in a external magnetic field B-->0, is described by taking into account the thermal and the zero-point fluctuations of stochastic electrodynamics. The inductor belongs to a RLC circuit without batteries and the random motion of the magnetic dipole generates in the solenoid a fluctuating current Idip(t), and a fluctuating voltage Edip(t), with spectral distribution quite different from the Nyquist noise. We show that the mean square value <I2dip> presents an enormous variation when the frequency of precession approaches the frequency of the circuit, but it is still much smaller than the Nyquist current in the circuit. However, we also show that <I2dip> can reach measurable values if the inductor is interacting with a macroscopic sample of magnetic particles (atoms or nuclei) which are close enough to its coils.

The interaction between a very thin macroscopic solenoid, and a single magnetic particle precessing in a external magnetic field Bo, is described by taking into account the thermal and the zero-point fluctuations of stochastic electrodynamics. The inductor belongs to a RLC circuit without batteries and the random motion of the magnetic dipole generates in the solenoid a fluctuating current &ip( 1), and a fluctuating voltage &ip( t). with spectral distribution quite different from the Nyquist noise. We show that the mean square value (Z~ip) presents an enormous variation when the frequency of precession approaches the frequency of the circuit, but it is still much smaller than the Nyquist current in the circuit. However, we also show that (I,&) can reach measurable values if the inductor is interacting with a macroscopic sample of magnetic particles (atoms or nuclei) which are close enough to its coils.

The interaction of a microscopic magnetic dipole and the inductor of a RLC circuit without batteries, is described using the approach of stochastic electrodynamics. The purpose of this study is to clarify the effects of the current fluctuations on the paramagnetic behaviour of a sample of magnetic material which is close to a thin solenoid. A suppression is predicted in the average magnetization, even in the case in which the circuit temperature is arbitrarily close to the absolute zero.

We analyze wave propagation in the vacuum of Podolsky regularized electrodynamics. Two kinds of waves were found in the theory: the traditional non-dispersive waves of Maxwell electrodynamics, and a dispersive wave reminiscent of wave propagation in a collisionless plasma. Charged particle concentration was determined, and found to be huge in this vacuum. We interpret the results in terms of vacuum polarization effects induced in an otherwise classical theory.

We analyze wave propagation in the vacuum of Podolsky regularized electrodynamics. Two kinds of waves were found in the theory: the traditional non-dispersive waves of Maxwell electrodynamics, and a dispersive wave reminiscent of wave propagation in a collisionless plasma. Charged particle concentration was determined, and found to be huge in this vacuum. We interpret the results in terms of vacuum polarization effects induced in an otherwise classical theory.

We present two models for the electron in classical electrodynamics, which include some effects from quantum electrodynamics. In the first model, the electron is treated as an extended particle owing to the high-frequency oscillations (Zitterbewegung) of its electrical charge. We show that this model predicts correctly the magnitude of the electron spin and it gives the electron the same gyromagnetic factor as predicted by Dirac equation without radiative corrections. In this model, the electron self-energy has a logarithmic divergence due to the extended distribution of its electric charge. In the second model, virtual pair creation around the electron is taken into account by a generalization of the lagrangian for the electromagnetic field that preserves the symmetries of classical electrodynamics. This generalization changes the interaction of the electron with the electromagnetic field at small distances and allows us to evaluate the self-force of a point particle in a consistent way. We show that the solutions of the derived equation of motion do not exhibit self-acceleration nor pre-acceleration, being consistent with causality.

We discuss, in the context of classical electrodynamics with a Lorentz invariant cutoff at short distances, the self-force acting on a point charged particle. It follows that the electromagnetic mass of the point charge occurs in the equation of motion in a form consistent with special relativity. We find that the exact equation of motion does not exhibit runaway solutions or non-causal behavior, when the cutoff is larger than half of the classical radius of the electron.

We present a simple non-Hermitian model to describe the phenomenon of asymmetric tunneling between two energy-degenerate sites coupled by a non-reciprocal interaction without dissipation. The system was described using a biorthogonal family of energy eigenvectors, the dynamics of the system was determined by the Schrödinger equation, and unitarity was effectively restored by proper normalization of the state vectors. The results show that the tunneling rates are indeed asymmetrical in this model, leading to an equilibrium that displays unequal occupation of the degenerate systems even in the absence of external interactions.

Inspired by a recently observed asymmetry in the transmission of circularly polarized light through a metamaterial, we present a non-hermitian PT-symmetric quantum model to describe the interaction of the light fields in two resonant cavities coupled via a 2D-chiral mirror. We compute the time evolution of the light fields in this model, find two sets of operators compatible with the hamiltonian in a delocalized representation, discover the energies of the system and show that the transmission probability predicted by the model is indeed asymmetric.

An updated overview of recent results on Heavy-Ion induced reactions of interest for neutrinoless double beta decay is reported in the framework of the NUMEN project. The NUMEN idea is to study heavy-ion induced Double Charge Exchange (DCE) reactions with the aim to get information on the nuclear matrix elements for neutrinoless double beta (0νββ) decay. Moreover, to infer the neutrino average masses from the possible measurement of the half- life of 0νββ decay, the knowledge of the nuclear matrix elements is a crucial aspect.

niture or to purchase additional equipment and exactly the same content was covered in the active learning and in the traditional lecture course sections. Qualitatively, observation of the students' attitudes during the term and analysis of the comments they made in the evaluation of the subject and of their teachers allowed us to conclude that the students perceive that engagement in their own learning affects positively their conceptual understanding and their problema solving skills, besides indicating that they prefer to be taught through an active methodology.

Electronic systems functionality degrades when these systems are operating in harsh environments such as those where they are exposed to ionizing radiation. Understanding and measuring these effects is extremely important in order to design systems that can operate reliably. This work discusses experimental data of heavy ion and x-ray radiation effects on a Commercial-Off-The-Shelf (COTS) low-cost microprocessor. The heavy ions test results suggest that, in this technology, the SRAM is more sensitive to SEE than flash memory. Ions with a LET higher than 5 MeV/mg/cm 2 may disrupt the device's proper operation.

Coupled oscillators are among the simplest composite quantum systems in which the interplay of entanglement and interaction may be explored. We examine the effects of coupling on the quantum fluctuations of the coordinates and momenta of the oscillators in a single-excitation entangled Bell-like state. We discover that coupling acts as a mechanism for noise transfer between one pair of coordinate and momentum and another. Through this noise transfer mechanism, the uncertainty product is lowered, on average, relatively to its non-coupled level for one pair of coordinate and momentum and it is enhanced for the other pair. This novel mechanism for noise transfer may be explored in precision measurements in entanglement-assisted sensing and metrology.