Study of single muons with the Large Volume Detector at Gran Sasso Laboratory

The present study is based on the sample of about 3 mln single muons observed by LVD at underground Gran Sasso Laboratory during 36500 live hours from June 1992 to February 1998. We have measured the muon intensity at slant depths from 3 km w.e. 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 of pion and kaon spectrum: 2.76 \pm 0.05. The reminders are horizontal muons produced by the neutrino interactions in the rock surrounding LVD. The value of this flux is obtained. The results are compared with Monte Carlo simulations and the world data.Comment: 13 pages, 2 figures, accepted for publication in "Physics of Atomic Nuclei

Muon `Depth -- Intensity' Relation Measured by LVD Underground Experiment and Cosmic-Ray Muon Spectrum at Sea Level

We present the analysis of the muon events with all muon multiplicities collected during 21804 hours of operation of the first LVD tower. The measured angular distribution of muon intensity has been converted to the `depth -- vertical intensity' relation in the depth range from 3 to 12 km w.e.. The analysis of this relation allowed to derive the power index, $\gamma$, of the primary all-nucleon spectrum: $\gamma=2.78 \pm 0.05$. The `depth -- vertical intensity' relation has been converted to standard rock and the comparison with the data of other experiments has been done. We present also the derived vertical muon spectrum at sea level.Comment: 7 pages, 3 figures, to be published on Phys. Rev.

Upper Limit on the Prompt Muon Flux Derived from the LVD Underground Experiment

We present the analysis of the muon events with all muon multiplicities collected during 21804 hours of operation of the first LVD tower. The measured depth-angular distribution of muon intensities has been used to obtain the normalization factor, A, the power index, gamma, of the primary all-nucleon spectrum and the ratio, R_c, of prompt muon flux to that of pi-mesons - the main parameters which determine the spectrum of cosmic ray muons at the sea level. The value of gamma = 2.77 +/- 0.05 (68% C.L.) and R_c < 2.0 x 10^-3 (95% C.L.) have been obtained. The upper limit to the prompt muon flux favours the models of charm production based on QGSM and the dual parton model.Comment: 10 pages, 4 figures, RevTex. To appear in Phys. Rev.

Search for chaotic features in the arrival times of air showers

We study sequences of times between successive arrivals of air showers detected in the EAS-TOP experiment (primary energy between 70 and 1000 TeV) in order to establish their nature, whether stochastic or chaotic

The shapes of the atmospheric Cherenkov light images from Extensive Air Showers

Experimental results on the shapes of atmospheric Cherenkov light images from Extensive Air Showers at E(0) = 10(13)-10(14) eV are presented, The results are based on data obtained by the first element of the Cherenkov light array of the EAS-TOP experiment at Campo Imperatore (2005 m a.s.l., National Gran Sasso Laboratories, Italy), Images are obtained with pixel field of view omega = 1.5 x 10(-5) sr and full field of view Omega approximate to 10(-3) sr. The shapes of the images agree with the expectations and their fluctuations are large and significant, Experimental data on the dependence of the image shapes on the detection geometry are reported, The images are well reproduced by two independent side by side detectors, within measured accuracies, Such accuracies (approximate to 15% for large photoelectron content) define the level at which each pixel content is related to the shower structure, The presence of events characterized by patterns with multiple structures is proved, It is shown that such features are related to physical fluctuations of the shower structure