Observação da variação sazonal de múons múltiplos no NOvA Near Detector
Nenhuma Miniatura disponível
Data
2018-04-26
Autores
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Federal de Goiás
Resumo
The interaction of a cosmic ray particle with an element of the atmosphere results in a cascade of
particles, known as extensive air showers, which can be divided into three main branches, known
as the hadronic, the electromagnetic, and the muonic component. As for the latter, since muons can
reach high depths underground, they are generally used to study cosmic rays at different
underground depths. The dynamics of extensive air showers is directly connected to the density of
the atmosphere, as it defines the probability of particles to decay or interact. As muons are mainly
produced from the decay of pions and kaons, and a warmer atmosphere results in higher number of
meson decays, such particles are prone to suffer a sea- sonality effect that is directly correlated to
the yearly seasonal variations of the atmosphere, an effect that has been verified by a large number
of experiments over the past six decades. In 2015 the MINOS experiment presented an anti
correlation between the effective temperature of the atmosphere and the seasonality of the muon
flux for multiplicities higher than one (i.e. more than one muon track per cosmic ray event). Said
anti correlation is not yet fully understood, counting with only a qualitative hypothesis as a
probable mechanism. As such, the main goals of this study are to verify the MINOS anti
correlation effect and extend the study to verify the seasonality of the effect as a function of
different variables in order to improve the understanding of the phenomenon and possible
corroborations with the known hypothesis. Two full years of the NOνA Near Detector, ranging
from April 2015 to April 2017, were used as the dataset for the analysis. The anti correlation
between the multiple muon flux and the effective temperature of the atmosphere is confirmed by
the NOνA Near Detector, being in full agreement with the results presented by the MINOS
Collaboration. The seasonal effect is also broken down by different variables: i) track separation,
ii) zenith angle, iii) track angular separation, and iv) multiplicity. Different regions of these
variables represent different energy ranges for the detected underground muons, their hadron
parents or the primary particles that originated the cosmic ray shower, being a way to verify any
particular dependency with energy. The results show that there are no clear trends in any of the
studied variables, except for the multiplicity, in which the intensity of the seasonal variation
increases for higher multiplicities.
Descrição
Palavras-chave
Citação
TOGNINI, S. C. Observação da variação sazonal de múons múltiplos no NOvA Near Detector. 2018. 160 f. Tese (Doutorado em Fisica) - Universidade Federal de Goiás, Goiânia, 2018.