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In this work we study sulfur confined between two multilayer graphene films under thermal treatments by means of electrical and Raman spectroscopy characterization. We found some similarities between the electrical behavior and differential scanning calorimetry of sulfur immersed into nanoporous anodic alumina template during sulfur phase transitions, this suggests that sulfur has a different thermal behavior when it is in confining conditions compared to the free state. In addition, multilayer graphene was exposed to sulfur vapors at 500 {\deg}C to induce chemical reaction. This method effectively produced covalent bonding between sulfur and multilayer graphene and a p-type doping of about 2x10^13 cm^-2 in charge concentration. Finally, based on first principle calculations we speculate on the existence of a new bidimensional structure of sulfur., Comment: 7 pages, 6 figures

The Antarctic region in which severe ozone depletion has taken place is known as the ozone hole. This region has two basic indicators: the area, where the ozone abundance is low (size), and the quantity of ozone mass deficit (depth). The energetic particles that penetrate deeply into the atmosphere and galactic cosmic rays (GCR) modify the ozone abundance in the stratosphere. With this research project, we are looking for evidence of a connection between variations in the cosmic ray flux and variations in the size of the ozone hole. In addition, we are looking for signs of the kind of processes that physically connect GCR fluxes with variations in the stratospheric ozone hole size (OHS) in the Antarctic region. With this goal in mind, we also analyze here the atmospheric temperature (AT) anomalies, which have often been linked with such variations. Using Morlet's wavelet spectral analysis to compute the coherence between two time series, we found that during the analyzed period (1982-2005), there existed a common signal of around 3 and 5 years between the OHS and GCR time series, during September and November, respectively. In both cases, the relationship showed a time-dependent anti-correlation between the two series. On the other hand, for October the analysis showed a time-dependent correlation that occurs around 1.7 years. These results seem to indicate that there exist at least two kinds of modulation processes of GCR fluxes on the OHS that work simultaneously but that change their relative relevance along the timeline., Comment: 14 pages and 4 figures

Comparison of P-P total cross-sections estimations at very high energies - from accelerators and cosmic rays - shows a disagreement amounting to more than 10 %, a discrepancy which is beyond statistical errors. Here we use a phenomenological model based on the Multiple-Diffraction approach to successfully describe data at accelerator energies. The predictions of the model are compared with data On the basis of regression analysis we determine confident error bands, analyzing the sensitivity of our predictions to the employed data for extrapolation. : using data at 546 and 1.8 TeV, our extrapolations for p-p total cross-sections are only compatible with the Akeno cosmic ray data, predicting a slower rise with energy than other cosmic ray results and other extrapolation methods. We discuss our results within the context of constraints in the light of future accelerator and cosmic ray experimental results., Comment: 26 pages aqnd 11 figures

Present estimations of proton-proton total cross section at very high energies are obtained from cosmic rays (>10^17 eV) by means of some approximations and the knowledge of the measured proton-air cross section at these energies. Besides, total cross section are measured with present day high energy colliders up to nearly 2 TeV in the center of mass (~ 10^15 eV in the laboratory). Here we use a phenomenological model based on the Multiple-Diffraction approach to succesfully describe data at accelerator energies. Then we estimate with it proton-proton total cross sections at cosmic ray energies. On the basis of a forecasting regression analysis we determine confident errors bands, analyzing the sensitivity of our predictions to the employed data for extrapolation., Comment: 9 pages, 2 figures

Proton-proton total cross sections are measured with present day high energy colliders up to 2 TeV in the centre-of-mass of the system (10^{15}) eV in the laboratory). Several parameterizations, very succesful at low energies, can then be used to extrapolate the measured values and get estimations of cross sections to higher energies (10^{17} eV). On the other hand, from very high energetic cosmic rays (> 10^{17} eV) and using some approximations, it is possible to get a value for proton-proton total cross section from the knowledge of the proton-proton total cross section at these energies. Here we use a phenomenological model to estimate proton-proton total cross section at cosmic ray energies. On the basis of regression analysis we show that the predictions are highly sensitive to the employed data for extrapolation. Using data at 1.8 TeV our extrapolations for proton-proton total cross section are incompatible with most of cosmic ray results, Comment: 4 pages, 2 figures

The data on source energy spectra of solar cosmic rays (SCR), i.e. the data on the spectrum form and on the absolute SCR are of interest for three reasons: (1) the SCR contain the energy comparable to the total energy of electromagnetic flare radiation (less than or equal to 10 to the 32nd power ergs); (2) the source spectrum form indicates a possible acceleration mechanism (or mechanism); and (3) the accelerated particles are efficiently involved in nuclear electromagnetic and plasma processes in the solar atmosphere. Therefore, the data on SCR source spectra are necessary for a theoretical description of the processes mentioned and for the formulation of the consistent flare model. Below it is attempted to sound solar particle sources by means of SCR energy spectrum obtained near the Sun, at the level of the roots of the interplanetary field lines in the upper solar corona. Data from approx. 60 solar proton events (SPE) between 1956-1981. These data were obtained mainly by the interplanetary demodulation of observed fluxes near the Earth. Further, a model of coronal azimuthal transport is used to demodulate those spectra, and to obtain the source energy spectra.

The study of charge changing cross sections of fast ions colliding with matter provides the fundamental basis for the analysis of the charge states produced in such interactions. Given the high degree of complexity of the phenomena, there is no theoretical treatment able to give a comprehensive description. In fact, the involved processes are very dependent on the basic parameters of the projectile, such as velocity charge state, and atomic number, and on the target parameters, the physical state (molecular, atomic or ionized matter) and density. The target velocity, may have also incidence on the process, through the temperature of the traversed medium. In addition, multiple electron transfer in single collisions intrincates more the phenomena. Though, in simplified cases, such as protons moving through atomic hydrogen, considerable agreement has been obtained between theory and experiments However, in general the available theoretical approaches have only limited validity in restricted regions of the basic parameters. Since most measurements of charge changing cross sections are performed in atomic matter at ambient temperature, models are commonly based on the assumption of targets at rest, however at Astrophysical scales, temperature displays a wide range in atomic and ionized matter. Therefore, due to the lack of experimental data , an attempt is made here to quantify temperature dependent cross sections on basis to somewhat arbitrary, but physically reasonable assumptions.