117993503
Search Capability for eta ---> nu(e, tau) anti-nu(e, tau) Decays in Cubic Kilometer Neutrino Detectors
We investigate the discovery potential of cubic-kilometer neutrino observatories such as IceCube to set stringent limits on the forbidden decays η → v e v e and η → v τ v τ . The signatures for these decays are cascade events resulting from the charged-current reactions of v e , v τ , v e , and v τ on nuclei in such detectors. Background cascade events are mainly due to v e 's from atmospheric μ, K + , and K 0 S decays and to a lesser extent from atmospheric v μ neutral-current interactions with nuclei. A direct upper limit for the branching ratio η → v e,τ v e,τ of 6.1 × 10 -4 at 90% CL can be achieved.
73620177
Cosmic Ray Proton Background Could Explain ATIC Electron Excess
We show that the excess in the Galactic electron flux recently published by Chang, et al. (Nature, 20 Nov. 2008) can have a simple methodical origin due to a contribution from misidentified proton induced electron-like events in the ATIC detector. A subtraction of the cosmic ray proton component from the published ATIC electron flux eliminates this excess in the range of 300 to 800 GeV.
128460124
On the accuracy of the primary energy and nuclei determination at mountain altitudes and sea level
The information carried by EAS of the energy range 10 14 – 10 17 eV is limited by significant fluctuations of the shower development, insufficient experimental sampling and uncertainties of the detector response. Additional uncertainties arise from different simulation procedures and statistical methods used for inferring the results. We propose to combine an advanced EAS simulation program like CORSIKA with the ANI multivariate statistical analysis package for an event-by-event analysis and for a standardization of the inference from EAS data. We illustrate the technique for simulated results of two different detector locations: ANI at a mountain altitude and KASCADE at sea level.
6435303
Rigidity-dependent cosmic ray energy spectra in the knee region obtained with the GAMMA experiment
On the basis of the extensive air shower (EAS) data obtained by the GAMMA experiment, the energy spectra and elemental composition of the primary cosmic rays are derived in the 10 3 –10 5 TeV energy range. The reconstruction of the primary energy spectra is carried out using an EAS inverse approach in the framework of the SIBYLL2.1 and QGSJET01 interaction models and the hypothesis of power-law primary energy spectra with rigidity-dependent knees. The energy spectra of primary H, He, O-like and Fe-like nuclei obtained with the SIBYLL interaction model agree with corresponding extrapolations of the balloon and satellite data to � 10 3 TeV energies. The energy spectra obtained from the QGSJET model show a predominantly proton composition in the knee region. The rigiditydependent knee feature of the primary energy spectra for each interaction model is displayed at the following rigidities: ER ’ 2500 � 200 TV (SIBYLL) and ER ’ 3100–4200 TV (QGSJET). All the results presented are derived taking into account the detector response, the reconstruction uncertainties of the EAS parameters, and fluctuations in the EAS development. � 2007 Elsevier B.V. All rights reserved. PACS: 96.40.Pq; 96.40.De; 96.40.� z; 98.70.Sa
15765199
About EAS size spectra and primary energy spectra in the knee region
Based on the unified analyses of KASCADE, AKENO, EAS-TOP and ANI EAS size spectra, the approximations of energy spectra of different primary nuclei have been found. Calculations were carried out using SIBYLL and QGSJET interaction models in 0.1-100 PeV primary energy range. The results point to existence of both rigidity-dependent steepening energy spectra at R=200-400 TV and an additional proton (neutron) component with differential energy spectrum (6.1+/-0.7)10^{-11}(E/Ek)^{-1.5} (m^2.s.sr.TeV)^{-1} before the knee Ek=2030+/-130 TeV and with power index g2=-3.1+/-0.05 after the knee.
103336904
Calibration of energy measured in Roentgen emulsion experiments. (In Russian)
17568500
An all-particle primary energy spectrum in the 3–200 PeV energy range
We present an all-particle primary cosmic-ray energy spectrum in the 3 × 10 6 – 2 × 10 8 GeV energy range obtained by a multi-parametric event-by-event evaluation of the primary energy. The results are obtained on the basis of an expanded EAS data set detected at mountain level (700 g cm −2 )b y the GAMMA experiment. The energy evaluation method has been developed using the EAS simulation with the SIBYLL interaction model taking into account the response of GAMMA detectors and reconstruction uncertainties of EAS parameters. Nearly unbiased (<5%) energy estimations regardless of a primary nuclear mass with an accuracy of about 15–10% in the 3 × 10 6 –2 × 10 8 GeV energy range respectively are attained. An irregularity (‘bump’) in the spectrum is observed at primary energies of ∼7.4 × 10 7 GeV. This bump exceeds a smooth power-law fit to the data by about 4 standard deviations. By not rejecting the stochastic nature of the bump completely, we examined the systematic uncertainties of our methods and conclude that they cannot be responsible for the observed feature.
15515326
Galactic diffuse gamma-ray flux at the energy about 175 TeV
We present an upper limit of galactic diffuse gamma-ray flux, measured with the GAMMA experiment at energy about 175 TeV. The results were obtained using selection of muon poor extensive air showers at mountain level (700 g/cm 2 , Mt. Ara- gats, Armenia) for 5 GeV muon energy threshold. An upper limit for the differential flux at energy E ≃ 175 +25 20 TeV is equal to (5.8 − 7.0) � 10 12 (ergm 2 � ssr) 1 for 95% confidence level 1 .