KASCADE-Grande measurements of energy spectra for elemental groups of cosmic rays

Abstract

The KASCADE-Grande air shower experiment [1] consists of, among others, a large scintillator array for measurements of charged particles, N ch , and of an array of shielded scintillation counters used for muon counting, N µ . KASCADE-Grande is optimized for cosmic ray measurements in the energy range 10 PeV to about 2000 PeV, where exploring the composition is of fundamental importance for understanding the transition from galactic to extragalactic origin of cosmic rays. Following earlier studies of the all-particle and the elemental spectra reconstructed in the knee energy range from KASCADE data [2], we have now extended these measurements to beyond 200 PeV. By analysing the two-dimensional shower size spectrum N ch vs. N µ for nearly vertical events, we reconstruct the energy spectra of different mass groups by means of unfolding methods over an energy range where the detector is fully efficient. The procedure and its results, which are derived based on the hadronic interaction model QGSJET-II-02 and which yield a strong indication for a dominance of heavy mass groups in the covered energy range and for a knee-like structure in the iron spectrum at around 80 PeV, are presented. This confirms and further refines the results obtained by other analyses of KASCADE-Grande data, which already gave evidence for a knee-like structure in the heavy component of cosmic rays at about 80 PeV [3].

Cosmic ray physics with ARGO-YBJ

“…The most evident features are observed by ARGO-YBJ around the positions $ 120 , $ 40 , and $ 60 , $ À5 , spatially consistent with the regions detected by Milagro [22]. These regions are observed with a statistical significance of about 15 s.d.…”

“…IVA and Table II). As known from literature [22,23], the deficit regions parallel to the excesses are due to using also the excess events to evaluate the background, which turns out to be overestimated. Symmetrically, deficit regions, if any, would be expected to be surrounded by weaker excess halos, which were not observed.…”

“…A clear knee structure is observed around 700 TeV. The p+He spectra by CREAM [14], ARGO-YBJ [6] and the hybrid experiment [20] below the knee, the spectra by Tibet AS [21] and KASCADE [22] above the knee are shown for comparison. In our result, the error bar is the statistical error, and the shaded area represents the systematic uncertainty [23] for details).…”

“…De Mitri As fully discussed in [22], various observables were considered and analyzed in order to find a 7 suitable estimator for the primary CR energy. Among them, according to MC simulations, N p8 , the 8 number of particles detected at ground within a distance of 8 m from the shower axis, resulted well 9 correlated with energy, not biased by the finite detector size and not much affected by shower to 10 shower fluctuations [22]. Nevertheless, as shown in Fig.…”

The 〈 ln A 〉 study with the Muon tracking detector in the KASCADE-Grande experiment – comparison of hadronic interaction models

“…The main conclusion from the analysis with the QGSJet-II-2+FLUKA model combination was that ln A is increasing with the energy, but its values are lower than expected in the energy range 10 16 eV -10 17 eV [17,18]. The reason for this are the distortions of the η distributions in simulations caused by the large number of high η muons that are shifting the η of the distributions towards higher values.…”