[en] This UHECR (ultra-high energy cosmic rays) workshop covers recent results from UHECR observations and theoretical developments as well as future plans. Review talks on the latest IceCube, IceTop, Auger, and TA results have been presented, and completed with papers from different inter-collaboration working groups on spectrum, composition, anisotropy, at the highest energy and in the transition region, and as well as on hadronic interactions in extensive air showers

[en] Observations of gamma-ray bursts in the 1 GeV-1 TeV energy region are of great interest for the understanding of these mysterious events. The detection of GeV-TeV gamma-ray bursts is feasible using extensive air shower arrays monitoring the fluctuations of the single-particle counting rate. The sensitivity is strongly increased working at mountain altitudes, in particular above 5000 m. In this paper they discuss the possibility to exploit the existing BASJE EAS array operating at Mt. Chacaltaya (Bolivia) at 5200 m a.s.l. Simulations of electromagnetic showers in the atmosphere have been performed in order to evaluate the sensitivity of this experiment to detect gamma ray bursts of different time duration, spectrum slope and energy cut-off. The detector can observe events of energy fluence F (E > 1 GeV) ∼ few 10^-5 erg cm^-2 comparable to that measured by satellite instruments during the most intense gamma-ray bursts, provided they occur at low zenith angles and assuming that the energy spectrum at least extends up to ∼ 1 TeV. In the case of events below the sensitivity of the experiment can be obtained by measurements in coincidence with satellite observations

[en] The present study is based on the sample of 2.9 x 10⁶ single muons observed by the Large Volume Detector (LVD) at the underground Gran Sasso Laboratory during 36 500 live hours from June 1992 to February 1998. We have measured the muon intensity at slant depths from 3 to 20 km w.e. Most events are high-energy downward muons produced by meson decay in the atmosphere. The analysis of these muons has revealed the power index γ of the π and K spectrum: γ = 2.76 ± 0.05. The remainders are horizontal muons produced by the neutrino interactions in the rock surrounding the LVD. The value of this flux near 90 degree sign is (6.1 ± 2.7) x 10^-13 cm^-2 s^-1 sr^-1. The results are compared with the Monte Carlo simulations and the world data

[en] The characteristics of the EAS-TOP extensive air shower array as a detector of very high energy cosmic rays (E₀ ≥ 10¹⁴ eV) for astrophysical studies are discussed. The array is located on top of the underground Gran Sasso Laboratory in central Italy; a subarray (11 modules of the em detector) has been operating since the end of 1987. From such data the stability of the detector, the timing resolution, the accuracies in the determination of the arrival directions (δθ = 1.2⁰ at E₀ ≅ 200 TeV in the present configuration) and in the reconstruction of the lateral electron distribution and of the shower size are derived. (orig.)

[en] A search for gamma-ray bursts in the GeV-TeV energy range has been performed by INCA, an air shower array working at 5200 m of altitude at the Chacaltaya Laboratory (Bolivia). The altitude of the detector and the use of the single-particle technique allows to lower the energy threshold up to few GeVs. No significant signals are observed during the occurrences of 125 GRBs detected by BATSE, and the obtained upper limits on the energy fluence in the interval 1-10³ (1-10²) GeV, range from 3.2 (8.6) x 10^-5 to 2.6 (7.0) x 10^-2 erg cm^-2 depending on the zenith angle of the events. These limits, thanks to the extreme altitude of INCA, are the lowest ever obtained in the sub-TeV energy region by a ground-based experiment

[en] The measurement of large-scale anisotropies in cosmic ray arrival directions at energies above 10¹³ eV is performed through the detection of extensive air showers (EAS) produced by cosmic ray interactions in the atmosphere. The observed anisotropies are small, so accurate measurements require small statistical uncertainties, i.e., large data sets. These can be obtained by employing ground detector arrays with large extensions (from 10⁴ to 10⁹ m²) and long operation time (up to 20 years). The control of such arrays is challenging and spurious variations in the counting rate due to instrumental effects (e.g., data taking interruptions or changes in the acceptance) and atmospheric effects (e.g., air temperature and pressure effects on EAS development) are usually present. These modulations must be corrected very precisely before performing standard anisotropy analyses, i.e., harmonic analysis of the counting rate versus local sidereal time. In this paper we discuss an alternative method to measure large-scale anisotropies, the 'East-West method'. It was originally proposed in the 1940s to study asymmetries in the flux of solar cosmic rays and later applied by Nagashima et al. to EAS at higher energies. It is a differential method, as it is based on the analysis of the difference of the counting rates in the east and west directions. Besides explaining the principle, we present here its mathematical derivation, showing that the method is largely independent of experimental effects, that is, it does not require corrections for acceptance and/or for atmospheric effects. We explain the use of the method to derive the amplitude and phase of the anisotropy and demonstrate its power under different conditions of detector operation.

[en] The amplitude and phase of the cosmic-ray anisotropy are well established experimentally between 10¹¹ eV and 10¹⁴ eV. The study of their evolution in the energy region 10¹⁴-10¹⁶ eV can provide a significant tool for the understanding of the steepening (^knee⁾ of the primary spectrum. In this Letter, we extend the EAS-TOP measurement performed at E ₀ ∼ 10¹⁴ eV to higher energies by using the full data set (eight years of data taking). Results derived at about 10¹⁴ and 4 x 10¹⁴ eV are compared and discussed. Hints of increasing amplitude and change of phase above 10¹⁴ eV are reported. The significance of the observation for the understanding of cosmic-ray propagation is discussed.

[en] We discuss the feasibility of a telescope consisting in a sampling array for extensive air showers measure combined with a muon tracking device. The sampling array will extend over a surface of ≥10⁷ m² while the muon tracking device will cover ≥10⁴ m². The telescope should be done with resistive plates counters and would become a very powerful device to study high energy neutrinos and gamma rays astronomy as well as cosmic ray physics up to the highest energy (≥10¹⁹ eV) region. (orig.)

[en] We present the results of three searches for correlations between ultra-high energy cosmic ray events (UHECRs) measured by Telescope Array and the Pierre Auger Observatory and high-energy neutrino candidate events from IceCube. Two cross-correlation analyses of UHECRs are done: one with 28 “cascades” from the IceCube ‘high-energy starting events’ sample and the other one with 12 high-energy “tracks”. The angular separation between the arrival directions of neutrinos and UHECRs is scanned. The same events are also used in a separate search stacking the neutrino arrival directions and using a maximum likelihood approach. We assume that UHECR magnetic deflections are inversely proportional to the energy with values 3°, 6° and 9° at 100 EeV to account for the various scenarios of the magnetic field strength and UHECR charges. A similar analysis is performed on stacked UHECR arrival directions and the IceCube 4-year sample of through-going muon-track events that was optimized for neutrino point source searches. (paper)

[en] The Large Volume Detector (LVD) has been continuously taking data since 1992 at the INFN Gran Sasso National Laboratory. The LVD is sensitive to neutrino bursts from gravitational stellar collapses with full detection probability over the Galaxy. We have searched for neutrino bursts in LVD data taken over 7,335 days of operation. No evidence of neutrino signals has been found between 1992 June and 2013 December. The 90% C.L. upper limit on the rate of core collapse and failed supernova explosions out to distances of 25 kpc is found to be 0.114 yr"−"1