CALET on the International Space Station: new direct measurements of cosmic-ray iron and nickel

The Calorimetric Electron Telescope (CALET), in operation on the International Space Station since 2015, collected a large sample of cosmic-ray over a wide energy interval. Approximately 20 million triggered events per month are recorded with energies > 10 GeV. The instrument identifies the charge of individual elements up to nickel and beyond and, thanks to a homogeneous lead-tungstate calorimeter, it measures the energy of cosmic-ray nuclei providing a direct measurement of their spectra. Iron and nickel spectra are a low background measurement with negligible contamination from spallation of higher mass elements. Iron and nickel nuclei play a key role in understanding the acceleration and propagation mechanisms of charged particles in our Galaxy. In this contribution a direct measurement of iron and nickel spectra, based on more than five years of data, are presented in the energy range from 10 GeV/n to 2 TeV/n and from 8.8 GeV/n to 240 GeV/n, respectively. The spectra are compatible within the errors with a single power law in the energy region from 50 GeV/n to 2 TeV/n and from 20 GeV/n to 240 GeV/n, respectively. Systematic uncertainties are detailed and the nickel to iron flux ratio is presented. This unprecedented measurement confirms that both elements have very similar fluxes in shape and energy dependence, suggesting that their origin, acceleration, and propagation might be explained invoking an identical mechanism in the energy range explored so far

CALET on the International Space Station: a precise measurement of the iron spectrum

The Calorimetric Electron Telescope (CALET) was launched on the International Space Station in 2015 and since then has collected a large sample of cosmic-ray charged particles over a wide energy. Thanks to a couple of layers of segmented plastic scintillators placed on top of the detector, the instrument is able to identify the charge of individual elements from proton to iron (and above). The imaging tungsten scintillating fiber calorimeter provides accurate particle tracking and the lead tungstate homogeneous calorimeter can measured the energy with a wide dynamic range. One of the CALET scientific objectives is to measure the energy spectra of cosmic rays to shed light on their acceleration and propagation in the Galaxy. By the observation in first five years, a precise measurement of the iron spectrum is now available in the range of kinetic energy per nucleon from 10 GeV/n to 2 TeV/n. The CALET’s result with a description of the analysis and details on systematic uncertainties will be illustrated. Also, a comparison with previous experiments’ results is given

Neutrino propagation in the Earth and emerging charged leptons with nuPyProp\texttt{nuPyProp}

Ultra-high-energy neutrinos serve as messengers of some of the highest energy astrophysical environments. Given that neutrinos are neutral and only interact via weak interactions, neutrinos can emerge from sources, traverse astronomical distances, and point back to their origins. Their weak interactions require large target volumes for neutrino detection. Using the Earth as a neutrino converter, terrestrial, sub-orbital, and satellite-based instruments are able to detect signals of neutrino-induced extensive air showers. In this paper, we describe the software code $\texttt{nuPyProp}$ that simulates tau neutrino and muon neutrino interactions in the Earth and predicts the spectrum of the $\tau$-lepton and muons that emerge. The $\texttt{nuPyProp}$ outputs are lookup tables of charged lepton exit probabilities and energies that can be used directly or as inputs to the $\texttt{nuSpaceSim}$ code designed to simulate optical and radio signals from extensive air showers induced by the emerging charged leptons. We describe the inputs to the code, demonstrate its flexibility and show selected results for $\tau$-lepton and muon exit probabilities and energy distributions. The $\texttt{nuPyProp}$ code is open source, available on github.Comment: 42 pages, 21 figures, code available at https://github.com/NuSpaceSim/nupypro