The cosmic ray proton, helium and CNO fluxes in the 100 TeV energy region from TeV muons and EAS atmospheric Cherenkov light observations of MACRO and EAS-TOP

The primary cosmic ray (CR) proton, helium and CNO fluxes in the energy range 80–300 TeV are studied at the National Gran Sasso Laboratories by means of EAS-TOP (Campo Imperatore, 2005 m a.s.l.) and MACRO (deep underground, 3100 m w.e., the surface energy threshold for a muon reaching the detector being Eth l about 1,3 TeV). By using the measurements of the proton spectrum obtained from the direct experiments and hadron flux data in the atmosphere, we obtain for the relative weights of the three components at 250 TeV: Jp : JHe : JCNO = (0,20 +/- 0,08 ) : (0,58 +/- 0,19) : (0:22 +/- 0:17). This corresponds to the dominance of helium over proton primaries at 100–1000 TeV, and a possible non-negligible contribution from CNO. The lateral distribution of Cherenkov light in Extensive Air Showers (EASs), which is related to the rate of energy deposit of the primary in the atmosphere, is measured for a selected proton and helium primary beam, and good agreement is found when compared with the one calculated with the CORSIKA/QGSJET simulation model

Temperature variations in the low stratosphere (50–200 hPa)monitored by means of the atmospheric muon flux

The dependence of the muon flux on the atmospheric parameters (pressure and temperature) is a well-known effect since long time ago. We have correlated the muon flux recorded by the electromagnetic detector of EAS-TOP with the atmospheric temperature (up to few hPa level) monitored by the radio-soundings of the ITAV—Aeronautica Militare at Pratica di Mare (Rome). A significant effect has been observed when the muon flux is correlated with the atmospheric temperature in the region 50–200 hPa, as expected, since this is the region where the mesons of first generation are produced. The technique has been applied to two short periods of strong temperature variations in the low stratosphere, showing that the temporal pattern of the temperature is fairly well reproduced by the variations of the muon flux. The main results of this analysis are presented

The cosmic ray primary composition in the "knee" region through the EAS electromagnetic and muon measurements at EAS-TOP

The evolution of the cosmic ray primary composition in the energy range 10(6)–10(7) GeV (i.e. the ‘‘knee’’ region) is studied by means of the e.m. and muon data of the Extensive Air Shower EAS-TOP array (Campo Imperatore, National Gran Sasso Laboratories). The measurement is performed through: (a) the correlated muon number (Nl) and shower size (Ne) spectra,and (b) the evolution of the average muon numbers and their distributions as a function of the shower size. From analysis (a) the dominance of helium primaries at the knee,and therefore the possibility that the knee itself is due to a break in their energy spectrum (at EHe k = (3,5 +/0,3) 10(6) GeV) are deduced. Concerning analysis (b), the measurement accuracies allow the classification in terms of three mass groups: light (p,He), intermediate (CNO),and heavy (Fe). At primary energies E0 circa 10(6) GeV the results are consistent with the extrapolations of the data from direct experiments. In the knee region the obtained evolution of the energy spectra leads to: (i) an average steep spectrum of the light mass group (gamma(p;He )> 3,1)), (ii) a spectrum of the intermediate mass group harder than the one of the light component (gamma(CNO) circa 2,75,possibly bending at ECNO k =(6–7) 10(6 )GeV), (iii) a constant slope for the spectrum of the heavy primaries (gamma(Fe) circa 2,3–2,7) consistent with the direct measurements. In the investigated energy range,the average primary mass increases from = 1,6–1,9 at E0 circa 1,5 10(6) GeV to =2,8–3,1 at E0 circa 1,5 10(7) GeV. The result supports the standard acceleration and propagation models of galactic cosmic rays that predict rigidity dependent cut-offs for the primary spectra of the different nuclei. The uncertainties connected to the hadronic interaction model (QGSJET in CORSIKA) used for the interpretation are discussed

Rejection Power of A Horizontal Rpc Telescope For Left and Right Coming Cosmic Muons

The possibility of performing neutrino astronomy by means of a detector above the ground depends critically on the feasibility of a rejection power on the order of 10(11) required to discriminate the enormous background of cosmic downward going muons from the signal of upward going muons produced by neutrinos. In order to check whether and how this rejection is obtainable, we have built in the Physics Department of the University of Bari a horizontal cosmic muon telescope (MINI) instrumented with resistive plate counters. By performing time-of-flight measurements, we have estimated the rejection power of our telescope for left and right coming cosmic muons. The rejection dependence on a few fundamental parameters like minimum number of points per track, telescope length, RPC time resolution and on trigger configuration has been investigated

The Muon Background From Backscattered Cosmic-ray Muons In A Surface Neutrino Detector

A technique has been proposed for constructing above-ground detectors of upwardgoing mouns produced by neutrinos. We have calculated the background in such a detector from cosmic-ray muons which pass underground, scatter, and emerge from the ground traveling upwards. Except for the region within 11-degrees of the horizon, this background is smaller than the unavoidable background from underground interactions of atmospheric neutrinos. The simulation included effects of ionization energy loss, multiple Coulomb scattering, large-angle single and plural scattering on nuclei, and elastic and inelastic scattering of muons on nucleons. The small background from scattered cosmic-ray hadrons was also estimated