M. Aglietta

Measurement of the cosmic ray hadron spectrum up to 30-TeV at mountain altitude: The Primary proton spectrum

Abstract The flux of cosmic ray hadrons at the atmospheric depth of 820 gxa0cm−2 has been measured by means of the EAS-TOP hadron calorimeter (Campo Imperatore, National Gran Sasso Laboratories, 2005 m a.s.l.). The hadron spectrum is well described by a single power law: S h (E h )=(2.25±0.21±0.34 sys )×10 −7 E h 1000 (−2.79±0.05) m −2 s −1 sr −1 GeV −1 overthe energy range 30 GeV–30 TeV. The procedure and the accuracy of the measurement are discussed. The primary proton spectrum is derived from the data by using the CORSIKA/QGSJET code to compute the local hadron flux as a function of the primary proton spectrum and to calculate and subtract the heavy nuclei contribution (basing on direct measurements). Over a wide energy range E0=0.5–50 TeV its best fit is given by a single power law: S(E 0 )=(9.8±1.1±1.6 sys )×10 −5 E 0 1000 (−2.80±0.06) m −2 s −1 sr −1 GeV −1 The validity of the CORSIKA/QGSJET code for such application has been checked using the EAS-TOP and KASCADE experimental data by reproducing the ratio of the measured hadron fluxes at the two experimental depths (820 and 1030 gxa0cm−2 respectively) at better than 10% in the considered energy range.The flux of cosmic ray hadrons at the atmospheric depth of 820 g/cm^2 has been measured by means of the EAS-TOP hadron calorimeter (Campo Imperatore, National Gran Sasso Laboratories, 2005 m a.s.l.). The hadron spectrum is well described by a single power law : S(E_h) = (2.25 +- 0.21 +- 0.34(sys)) 10^(-7)(E_h/1000)^(-2.79 +- 0.05) m^(-2) s^(-1) sr^(-1) GeV^(-1) over the energy range 30 GeV-30 TeV. The procedure and the accuracy of the measurement are discussed. The primary proton spectrum is derived from the data by using the CORSIKA/QGSJET code to compute the local hadron flux as a function of the primary proton spectrum and to calculate and subtract the heavy nuclei contribution (basing on direct measurements). Over a wide energy range E_0 = 0.5-50 TeV its best fit is given by a single power law : S(E_0) = (9.8 +- 1.1 +- 1.6(sys)) 10^(-5) (E_0/1000)^(-2.80 +- 0.06) m^(-2) s^(-1) sr^(-1) GeV^(-1). The validity of the CORSIKA/QGSJET code for such application has been checked using the EAS-TOP and KASCADE experimental data by reproducing the ratio of the measured hadron fluxes at the two experimental depths (820 and 1030 g/cm^2 respectively) at better than 10% in the considered energy range.

Search for fractionally charged particles in the Mont Blanc LSD scintillation detector

Abstract An analysis of the events recorded by the Mont Blanc Neutrino Scintillation Detector was performed in order to search for fractionally charged particles with |Q| = 1 3 and |Q| = 2 3 . In a live time of 2378 days, the obtained 90% C. L. upper limits on the fluxes of fractionally charged particles in the core of our detector are Φ(|Q| = 1 3 ) −13 cm −2 s −1 sr −1 and Φ(|Q| = 2 3 ) −13 cm −2 s −1 sr −1 , the best available limits obtained by scintillation counters technique.

Search for 100 TeV gamma-ray emission from the Galactic disk

Upper limits have been obtained to the diffuse gamma-ray emission from the Galactic disk. The limits I(gamma)/I(p) less than 0.2 percent, i.e., I(gamma)(greater than 130 TeV) less than 3.2 x 10 exp -13/q cm/s/rad provide the first measurement obtained in the angular window corresponding to the distribution of the ISM. It is still, however, a factor of about 30 higher than the flux calculated from the cosmic ray interactions by Berezinsky and Kudryavtsev (1990). A lower limit of gamma greater than 2.3 is obtained to the power-law index of the differential energy spectrum of Galactic gamma rays from 100 MeV to 100 TeV, setting a limit to the possibility of a hard extrapolation of the Galactic gamma-ray spectrum to the 100 TeV region. 21 refs.

Imaging of atmospheric EAS Cherenkov light at EAS-TOP

SummaryImages of atmospheric EAS Cherenkov light have been recorded in connection with the EAS-TOP experiment. We describe the technique (based on a multianode photomultiplier Philips XP4702) and present some preliminary data analysis.

Fractal behavior of cosmic ray time series: Chaos or stochasticity?

This paper presents results on the fractal and statistical behavior of cosmic ray time series detected in an air shower experiment located at 2000-m altitude above the underground Gran Sasso Laboratory, Italy. We consider single particles (muons), corresponding to primary energies of ≥10 GeV, and air showers, corresponding to primary energies of ≥80 TeV. For all time series the analysis indicates a clear stochastic monofractal, non-Gaussian character; comparing these results with those obtained for underground muons and for neutron monitors, we conclude that these properties likely belong in general to cosmic ray time series, irrespective of the nature of the particles and the energies of their progenitors. In particular, the air shower time series from high-energy primaries have a fractal dimension larger than the single-muon time series originating from low-energy primaries.

The EAS-TOP atmospheric-Čerenkov-light telescope and its combined operation with the e.m. Detector

SummaryThe study of extensive air showers is performed at EAS-TOP by means of the combined operation of the first imaging Čerenkov telescope and the particle e.m. array. We discuss the technical characteristics of the Čerenkov detector and its resolutions. First data on the shape of the Čerenkov-light spots as a function of the EAS detection geometry, and on a first approach to the study of the longitudinal development of the cascades are also presented.

The EAS-TOP array at Gran Sasso: results of the electromagnetic detector

Abstract The detector of the e.m. component of Extensive Air Showers of the EAS-TOP array at Gran Sasso has been in operation for part of 1988 and 1989. We present the results obtained at primary energy Eγ ≈ 150 TeV in the study of the candidate sources observable in the northern emisphere. The observations of Cygnus X-3 during the radio burst of June 89 are discussed.

The EAS-TOP calorimeter

SummaryThe muon-hadron detector of EAS-TOP is a 270 m2 calorimeter constructed inside the air shower array on the top of the underground Gran Sasso Laboratory (Italy). The general layout of the detector and the performances of the active part (streamer and proportional chambers) are presented.

Primary cosmic ray composition in the 1013 – 1017 eV energy range from the analysis of multiple muon events in the NUSEX experiment

Abstract Absolute multiple muon rates have been measured in the NUSEX detector at Mont Blanc during more than 6 years of data taking. We present here a comparison with the expected rates according to different current models of primary cosmeric ray composition in the energy range 1013–1017 eV. The predictions are based on a Monte Carlo simulation of the atmospheric cascade including the most recent accelerator results on the hadronic interactions.

Search for low-energy νe, μ, τ and\(\bar \nu _{e,\mu ,\tau } \) in coincidence with BATSE gamma-ray burstsin coincidence with BATSE gamma-ray bursts

SummarySince neutrinos and gamma-rays productions are often associated in many astrophysical processes, the detection of neutrinos in correlation with γ-ray bursts (GRBs) could be a very important step towards the discovery of the sources of these events. A search for low-energy neutrinos of all flavours in correlation with ≈ 200 γ-ray bursts detected by BATSE aboard the Compton Observatory has been performed by the LSD (Liquid-Scintillator Detector) neutrino telescope. This kind of telescope, differently from the water Čerenkov detectors, is also sensitive to νμ, τ andn