A measurement of the energy spectra of cosmic-ray positrons and electrons was made with a balloon-borne magnet-spectrometer, which was flown at a mean geomagnetic cut-off of 4.5 GV/c. The observed ...positron flux in the energy range 7–16 GeV is approximately an order of magnitude lower than that of electrons, as measured in other experiments at various energies. The power law spectral index of the observed differential energy spectrum of electrons is $-2.89 \pm 0.10$ in the energy interval 7.5–47 GeV. For positrons the overall fit of the available data above 7 GeV has been considered. The spectral index is found to be $-3.37 \pm 0.26$ and the fraction of positrons, $\rm e^{+}$/($\rm e^{+}$ + $\rm e^{-}$), has a mean value of $0.064 \pm 0.003$. The world data on $\rm e^{+}$/($\rm e^{+}$ + $\rm e^{-}$) from 0.1 to 30 GeV indicate that a plerion type electron spectrum is preferred over the other types. The trend of the presently existing high energy data also suggests a possible contribution of positrons produced at the pulsar polar cap. High resolution experiments capable of identifying positrons at least up to 100 GeV with high statistics are required to pinpoint the origin of both electrons and positrons in the cosmic radiation.
A new measurement of the primary cosmic-ray proton and helium fluxes from 3 to 350 GeV was carried out by the balloon-borne CAPRICE experiment in 1998. This experimental setup combines different ...detector techniques and has excellent particle discrimination capabilities allowing clear particle identification. Our experiment has the capability to determine accurately detector selection efficiencies and systematic errors associated with them. Furthermore, it can check for the first time the energy determined by the magnet spectrometer by using the Cherenkov angle measured by the RICH detector well above 20 GeV
n
−1. The analysis of the primary proton and helium components is described here and the results are compared with other recent measurements using other magnet spectrometers. The observed energy spectra at the top of the atmosphere can be represented by (1.27±0.09)×10
4
E
−2.75±0.02 particles (m
2
GeV
sr
s)
−1, where
E is the kinetic energy in GeV, for protons between 20 and 350 GeV and (4.8±0.8)×10
2
E
−2.67±0.03 particles (m
2
GeV
n
−1
sr
s)
−1, where
E is the kinetic energy in GeV per nucleon, for helium nuclei between 15 and 150 GeV
n
−1.
A
bstract
The ANTARES neutrino telescope has an energy threshold of a few tens of GeV. This allows to study the phenomenon of atmospheric muon neutrino disappearance due to neutrino oscillations. In ...a similar way, constraints on the 3+1 neutrino model, which foresees the existence of one sterile neutrino, can be inferred. Using data collected by the ANTARES neutrino telescope from 2007 to 2016, a new measurement of Δ
m
32
2
and
θ
23
has been performed — which is consistent with world best-fit values — and constraints on the 3+1 neutrino model have been derived.
In this paper, a time-integrated search for point sources of cosmic neutrinos is presented using the data collected from 2007 to 2010 by the ANTARES neutrino telescope. No statistically significant ...signal has been found and upper limits on the neutrino flux have been obtained. Assuming an E super(-2) sub(v) spectrum, these flux limits are at 1-10x10 super(-8) GeV cm super(-2) s super(-1) for declinations ranging from -90degrees to 40degrees. Limits for specific models of RX J1713.7-3946 and Vela X, which include information on the source morphology and spectrum, are also given.
Abstract
A search for astrophysical pointlike neutrino sources using the data collected by the ANTARES detector between 2007 January 29 and 2017 December 31 is presented. A likelihood method is used ...to assess the significance of an excess of muon neutrinos inducing track-like events in correlation with the location of a list of possible sources. Different sets of objects are tested in the analysis: (a) a subsample of the Fermi 3LAC catalog of blazars, (b) a jet-obscured population of active galactic nuclei, (c) a sample of hard X-ray selected radio galaxies, (d) a star-forming galaxy catalog, and (e) a public sample of 56 very-high-energy track events from the IceCube experiment. None of the tested sources shows a significant association with the sample of neutrinos detected by ANTARES. The smallest
p
-value is obtained for the catalog of radio galaxies with an equal-weights hypothesis, with a pre-trial
p
-value equivalent to a 2.8
σ
excess, which is equivalent to 1.6
σ
post-trial. In addition, the results of a dedicated analysis for the blazar MG3 J225517+2409 are also reported: this source is found to be the most significant within the Fermi 3LAC sample, with five ANTARES events located less than one degree from the source. This blazar showed evidence of flaring activity in Fermi data, in spacetime coincidence with a high-energy track detected by IceCube. An a posteriori significance of 2.6
σ
for the combination of ANTARES and IceCube data is reported.
Monte Carlo simulations are a unique tool to check the response of a detector and to monitor its performance. For a deep-sea neutrino telescope, the variability of the environmental conditions that ...can affect the behaviour of the data acquisition system must be considered, in addition to a reliable description of the active parts of the detector and of the features of physics events, in order to produce a realistic set of simulated events. In this paper, the software tools used to produce neutrino and cosmic ray signatures in the telescope and the strategy developed to represent the time evolution of the natural environment and of the detector efficiency are described.
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