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In this article we present results of the study on the association betweenthe muon flux variation at ground level, registered by the\textit{\textit{New-Tupi}} muon telescopes ($22^0 53'00''S,\; 43^0 06'13'W$; 3m above sea level) and a geomagnetic storm of 25\,--\,29 August 2015 that hasraged for several days as a result of a coronal mass ejection (CME) impact onEarth's magnetosphere. A sequence of events started with an M3.5 X-ray classflare on 22 August 2015 at 21:19 UTC. The \textit{\textit{New-Tupi}} muontelescopes observed a Forbush decrease (FD) triggered by this geomagneticstorm, with onset on 26 August 2015. After the Earth crossed a heliosphericcurrent sheet (HCS), an increase in the particle flux was observed on 28 August2015 by spacecrafts and ground level detectors. The observed peak was intemporal coincidence with the impact of a high speed stream (HSS). We studythis increase, that has been observed with a significance above 1.5\% by groundlevel detectors in different rigidity regimes. We also estimate the lower limitof the energy fluence injected on Earth. In addition, we consider the origin ofthis increase, such as acceleration of particles by shock waves on the front ofthe HSS and the focusing effect of the HCS crossing. Our results show possibleevidence of a prolonged energetic (up to GeV energies) particle injectionwithin the Earth atmosphere system, driven by the HSS. In most cases theseinjected particles are directed to polar regions. However, the particles fromthe high energy tail of the spectrum can reach middle latitudes, and that couldhave consequences for the atmospheric chemistry, for instance, the creation ofNOx species may be enhanced and can lead to increased ozone depletion. Thistopic requires further study.

Muon Excess at Sea Level during the Progress of a Geomagnetic Storm and High Speed Stream Impact Near the Time of Eath's Heliospheric Sheet Crossing