Abstract
The Cosmic-Ray Extremely Distributed Observatory (CREDO) was established to detect and study ultra high-energy cosmic ray particles. In addition to making use of traditional methods for finding rare and extended cosmic ray events such as professional-grade Extensive Air Shower (EAS) arrays, as well as educational ‘class-room’ detectors, CREDO also makes use of cameras in smartphones as particle detectors. Beyond the primary scientific goal of the CREDO project, to detect Cosmic Ray Ensembles, is the equally important educational goal of the project. To use smartphones for EAS detection, it is necessary to demonstrate that they are capable of effectively registering relativistic charged particles. In this article, we show that the events recorded in the CREDO project database are indeed tracing incoherent cosmic ray muons. The specific observed distribution of zenith angle of charged particle direction corresponds to that expected for muons. It is difficult, if not impossible, to imagine different mechanisms leading to such a distribution, and we believe it clearly demonstrates the suitability of smartphone-based detectors in supporting the more traditional cosmic ray detectors.
Highlights
The cosmic ray energy spectrum extends from below ∼100 MeV [1] up to ∼1020 eV [2].The spectrum and composition of cosmic rays for energies up to the “knee” is compatible with diffusive shock acceleration mechanisms [3]
We study the distribution of the length of the tracks recorded on smartphone photos stored in the Cosmic-Ray Extremely Distributed Observatory (CREDO) database, in order to determine whether it is consistent with the zenith angle distribution of the muon (∼cos2(Θ))
Predictions assuming that we are dealing with the cosmic ray muons with the known zenith angle distribution are shown
Summary
The cosmic ray energy spectrum extends from below ∼100 MeV [1] up to ∼1020 eV [2]. The spectrum and composition of cosmic rays for energies up to the “knee” is compatible with diffusive shock acceleration mechanisms [3]. One of them is a focus of the Cosmic-Ray Extremely Distributed Observatory (CREDO) Collaboration This global approach allows the testing of hypothesized events of ultra-high energy cosmic ray ‘bunches’ observed as simultaneous Extensive Air Showers (EAS) over the entire exposed surface of the Earth: so-called Cosmic Ray Ensembles (CRE) [7,8,9]. Such a phenomenon has never been seen, but there are several models under which such an event is a possibility.
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