Gallone Samples Archive: a resource for Cultural Heritage studies

A vast collection of samples from artworks. A unique resource for future research in the field of conservation: investigating samples, implementing more advanced techniques

Optimisation Study of the Fabry-Pérot Optical Cavity for the MARIX/BRIXS Compton X-Ray Source

We present the study of the optimization of the optical cavity parameters, in order to maximise the flux of scattered photons in the Compton scattering process. In the optimisation, we compensate the losses of the photon number due to the elliptical shape of the laser pulse in optical cavity with a high focusing electron beam

Temperature-dependent criticality in random 2D Ising models

We consider 2D random Ising ferromagnetic models, where quenched disorder is represented either by random local magnetic fields (random-field Ising model) or by a random distribution of interaction couplings (random-bond Ising model). In both cases, we first perform zero- and finite-temperature Monte Carlo simulations to determine how the critical temperature depends on the disorder parameter. We then focus on the reversal transition triggered by an external field and study the associated Barkhausen noise. Our main result is that the critical exponents characterizing the power law associated with the Barkhausen noise exhibit a temperature dependence in line with existing experimental observations

Magneto-optical Kerr effect (MOKE) measurements with uniform laser profiles

The probability distribution of the amplitude DeltaM of Barkhausen jumps during magnetization reversal in thin films can be measured with optical techniques since each jump produces a variation DeltaI of the laser beam intensity used to probe magnetization. Here we present a theoretical model which demonstrates that no distortion takes place if P(DeltaM) is a power law P(DeltaM)=DeltaM^(-alpha) with alpha >= 1.0. This prediction has been experimentally confirmed by measuring P(DeltaI) in the same experimental conditions but in two different ways: first with a Gaussian and then with a constant intensity laser profile. In both cases the same power-law distribution has been observed with alpha=1

Dynamic Phase Transition in 2D Ising Systems: Effect of Anisotropy and Defects

We investigate the dynamic phase transition in two-dimensional Ising models whose equilibrium characteristics are influenced by either anisotropic interactions or quenched defects. The presence of anisotropy reduces the dynamical critical temperature, leading to the expected result that the critical temperature approaches zero in the full-anisotropy limit. We show that a comprehensive understanding of the dynamic behavior of systems with quenched defects requires a generalized definition of the dynamic order parameter. By doing so, we demonstrate that the inclusion of quenched defects lowers the dynamic critical temperature as well, with a linear trend across the range of defect fractions considered. We also explore if and how it is possible to predict the dynamic behavior of specific magnetic systems with quenched randomness. Various geometric quantities, such as a defect potential index, the defect dipole moment, and the properties of the defect Delaunay triangulation, prove useful for this purpose