Marlos da Silva

MULTITAPER SPECTRAL ANALYSIS OF COSMIC RAYS S ˜ AO MARTINHO DA SERRA'S MUON TELESCOPE AND NEWARK'S NEUTRON MONITOR DATA

In this work we present an analysis on the correction efficiency of atmospheric effects on cosmic ray S ˜ ao Martinho da Serras muon telescope and Newarks neutron monitor data. We use a Multitaper spectral analysis of cosmic rays time series to show the main periodicities present in the corrected and uncorrected data for the atmospheric effects. This kind of correction is very important when intends to study cosmic rays variations of extra-terrestrial origin.

Multi-spacecraft observations to study the shock extension in the inner heliosphere

The two Helios probes traveled at variable longitudinal and radial separations through the inner heliosphere. They collected most valuable high resolution plasma and magnetic field data for an entire solar cycle. The mission is still so successful that no other missions will collect the same kind of data in the next 20 years. One of the subjects studied after the success of the Helios mission was the identification of more than 390 shock waves driven by Interplanetary Coronal Mass Ejections (ICMEs). Combining the data from both probes, we make a statistical study for the extension of the shock waves in the interplanetary medium. For longitudinal separations of 90◦ we found a cutoff value at this angular separation. A shock has 50% of chance to be observed by both probes and the same probability for not being observed by two spacecrafts at the same time, when the angle between them is around 90◦. We describe the dependence of the probability for shocks to be observed by both probes with decreasing spacecraft separation. Including plasma data from the ISEE-3 and IMP-8 spacecrafts improves our statistical evaluation substantially.

Analysis of geomagnetic storm variations and count-rate of cosmic ray muons recorded at the Brazilian southern space observatory

An analysis of geomagnetic storm variations and the count rate of cosmic ray muons recorded at the Brazilian Southern Space Observatory - OES/CRS/INPE-MCT, in SMartinho da Serra, RS during the month of November 2004, is presented in this paper. The geomagnetic measurements are done by a three component low noise fluxgate magnetometer and the count rates of cosmic ray muons are recorded by a Muon Scintilator Telescope - MST, both instruments installed at the Observatory. The fluxgate magnetometer measures variations in the three orthogonal components of Earth magnetic field, H (North-South), D (East-West) and Z (Vertical), with data sampling rate of 0.5 Hz. The Muon Scintilator Telescope records hourly count rates. The arrival of a solar disturbance can be identified by observing the decrease in the muon count rate. The goal of this work is to describe the physical morphology and phenomenology observed during the geomagnetic storm of November 2004, using the H component of the geomagnetic field and vertical channel V of the multi-directional muon detector in South of Brazil.