A. C. Fauth

Muon excess at sea level from solar flares in association with the Fermi GBM spacecraft detector

This paper presents results of an ongoing survey on the associations between muon excesses at ground level registered by the Tupi telescopes and transient solar events, two solar flares whose gamma-ray and X-ray emissions were reported by, respectively, the Fermi GBM and the GOES 14. We show that solar flares of small scale, those with prompt X-ray emission classified by GOES as C-Class (power 10 to 10 W m at 1 AU) may give rise to muon excess probably associated with solar protons and ions emitted by the flare and arriving at the Earth as a coherent particle pulse. The Tupi telescopes are within the central region of the South Atlantic Anomaly (SAA), which allows particle detectors to achieve a low rigidity of response to primary and secondary charged particles (≥ 0.1 GV). Here we argue for the possibility of a “scale-free” energy distribution of particles accelerated by solar flares. Large and small scale flares have the same energy spectrum up to energies exceeding the pion production, the difference between them is only the intensity. If this hypothesis is correct, the Tupi telescope is registering muons produced by protons (ions)

Signals at ground level of relativistic solar particles associated with a radiation storm on 2014 April 18

Far away from any sunspot, a bright flare erupted on November 1st, 2014, with onset at 4:44 UT and a duration of around three hours, causing a C2.7-class flare. The blast was associated with the sudden disappearance of a large dark solar filament. The rest of the filament flew out into space, forming the core of a massive CME. Despite the location of the explosion over the sun’s southeastern region (near the eastern edge of the sun) not be geoeffective, a radiation storm, that is, solar energetic particles (SEP) started to reach the Earth around 14:00 UT, reaching the condition of an S1 (minor) radiation storm level on Nov. 2th. In coincidence with onset of the S1 radiation storm (SEP above 5 MeV), the Tupi telescopes located at 22090′S; 43020′W, within the South Atlantic Anomaly (SAA) detected a muon enhancement caused by relativistic protons from this solar blast. In addition an increase in the particle intensity was found also at South Pole neutron monitor. This means that there was a transverse propagation to the interplanetary magnetic field of energetic solar particles. However, we show that perpendicular diffusion alone cannot explain these observations, it is necessary a combination with further processes as a very high speed, at least of a fraction the CME shocks, close to the ecliptic plane.

Medida da vida média do múon

Neste trabalho foram utilizados um detector de particulas e um osciloscopio digital para medir a vida media do muon. O metodo experimental utilizado foi a medida do intervalo de tempo entre o sinal do muon e o do eletron do seu decaimento atraves do osciloscopio. Os muons desse experimento foram aqueles da radiacao cosmica e um unico detector utilizou o efeito Cherenkov na agua para medir tanto o sinal do muon como o sinal do eletron. Utilizando o espectro diferencial do alcance de muons verticais e a sua distribuicao angular obtivemos a taxa de decaimento de muons por massa do detector, TM = 13 x 10-3 [Hz/kg], que permite estimar a taxa de decaimento de muons ao nivel do mar para um detector com massa M. O tempo medio obtido para a vida dos muons foi de 1,87 ± 0,75 ms e esta em acordo com o valor apresentado pelo Particle Data Group.