Astroparticle physics

The H.E.S.S. experiment in Namibia, Africa, is a high energy gamma ray telescope sensitive in the energy range from $ 100 Gev to a few tens of TeV, via the use of the atmospheric Cherenkov technique. To minimize the systematic errors on the derived fluxes of the measured sources, one has to calculate the impact of the atmospheric properties, in particular the extinction parameter of the Cherenkov light ($ 300–650 nm) exploited to observe and reconstruct atmospheric particle showers initiated by gamma-ray photons. A lidar can provide this kind of information for some given wavelengths within this range. In this paper we report on the hardware components, operation and data acquisition of such a system installed at the H.E.S.S. site.

Unexplained periodic fluctuations in the decay rates of 32 Si and 226 Ra have been reported by groups at Brookhaven National Laboratory ( 32 Si), and at the Physikalisch-Technische-Bundesandstalt in Germany ( 226 Ra). We show from an analysis of the raw data in these experiments that the observed fluctuations are strongly correlated in time, not only with each other, but also with the distance between the Earth and the Sun. Some implications of these results are also discussed, including the suggestion that discrepancies in published half-life determinations for these and other nuclides may be attributable in part to differences in solar activity during the course of the various experiments, or to seasonal variations in fundamental constants.

Over time a few physicists have held out hope and suggested that the elusive (sterile) neutrino might actually be a disguised tachyon and could be the key to unraveling some of the universe's best-kept secrets.
The tachyon ... a hypothetical particle that always moves faster than light ... could reveal a plausible answer in e.g. Dark and Anti Matter (?)

The neutrino synchrotron process has been considered within the framework of the electro-weak theory. An electron moving in a magnetic field with spiral path changes the Landau level to release the energy in terms of neutrino antineutrino pair. The calculation of scattering cross-section for the neutrino synchrotron radiation has been carried out. We also calculate the energy loss rate and compare our result with LandstreetÕs result, graphically. Finally, the neutrino luminosity (expressed in the unit of solar luminosity) at different central temperatures of white dwarfs and neutron stars have been calculated to study the significance of this process in the later stages of the stellar evolution.

We discuss, in the framework of induced gravity, singularity free cosmologies, deriving a class of exact solutions depending on the form of gravitational coupling and of interaction potential. The basic principle from which such cosmologies are derived, is the fact that, in a more general theory, cosmological singularities can be removed considering conservation laws always and absolutely valid. It is very important to stress that we find a fine agreement among the solutions and the data coming from all recent observational campaigns.

The PAMELA experiment is a satellite-borne apparatus designed to study charged particles in the cosmic radiation with a particular focus on antiparticles. PAMELA is mounted on the Resurs DK1 satellite that was launched from the Baikonur cosmodrome on June 15th 2006. The PAMELA apparatus comprises a time-of-flight system, a magnetic spectrometer, a silicon-tungsten electromagnetic calorimeter, an anticoincidence system, a shower tail catcher scintillator and a neutron detector. The combination of these devices allows antiparticles to be reliably identified from a large background of other charged particles. This paper reviews 0927-6505/$ -see front matter Ó (R. Sparvoli). z Deceased.

A superluminal quantum-vortex model of the electron and the positron is produced from a superluminal double-helix model of the photon during electron-positron pair production. The two oppositely-charged (with Q = ±e sqrt (2/α) = 16.6e) open-helix spin-½ half-photons compose the double-helix photon. These half-photons separate and curl up their separated superluminal single-helical trajectories to form an electrically-charged superluminal closed-helix spin-½ quantum-vortex electron model and a corresponding positron model. The helical radius and the Dirac equation's zitterbewegung angular frequency of the quantum vortex electron and positron models equal the helical radius and zitterbewegung angular frequency of the two spin-½ half-photons, each of energy E = mc^2 , that composed the double-helix photon model of energy E = 2mc^2 from which the electron and positron models were produced. The photon and electron models are also compatible when a photon of energy E > 2mc^2 produces a relativistic electron-positron pair. Implications of the quantum vortex electron model for electron stability are discussed.

The emission of gravitational waves from a system of massive objects interacting on elliptical, hyperbolic and parabolic orbits is studied in the quadrupole approximation. Analytical expressions are then derived for the gravitational wave luminosity, the total energy output and gravitational radiation amplitude. A crude estimate of the expected number of events towards peculiar targets (i.e. globular clusters) is also given. In particular, the rate of events per year is obtained for the dense stellar cluster at the Galactic Center.

Additional experimental evidence is presented in support of the recent hypothesis that a possible solar influence could explain fluctuations observed in the measured decay rates of some isotopes. These data were obtained during routine weekly calibrations of an instrument used for radiological safety at The Ohio State University Research Reactor using 36 Cl. The detector system used was based on a Geiger-Müller gas detector, which is a robust detector system with very low susceptibility to environmental changes. A clear annual variation is evident in the data, with a maximum relative count rate observed in January/February, and a minimum relative count rate observed in July/August, for seven successive years from July 2005 to June 2011. This annual variation is not likely to have arisen from changes in the detector surroundings, as we show here.

In order to study a physical system, one has to disturb the experimental set up, that is a perturbation is required and experimental and high energy physics is to a large extent about stabilizing perturbed experimental systems. In this paper, we shall apply quantum mechanical perturbation theory; particularly time independent perturbation theory to the Biefeld Brown effect and make a generalization to antigravity effects of the Boris Volfson gravito-phonon maser. Correction In Text: Edward Leedskalnin, New Grange Florida, U.S.A 1947 A.D. & Not Ned Nidskalnin-(Nephew of John Carter Of Mars or "Bossom"!)
In addition to Human/Alien Engineered Space Craft Models such as the T-30; also believed to have been engineered under the 1930's PROJECT RAINBOW Super-Secret U.S. Military Space Programs (General Relativity Published Comprehensively in 1920 by the way) is the TR-3B, also a Triangular Design Spacecraft Bible Book Of Mathew Chapter 27 "Holy City"-as in Holy City Los Angeles California Sized Antigravity Craft which use Rotating Pyramids Mechanisms place at the Vertices for Gravitational Wave Propulsion. Clockwise Rotations anywhere in the Exodus 24: 9-11 Universe propelling the Spacecraft towards Orion's Belt (The Heavenly Jerusalem Emeritus-Bible Book Of Acts) and similarly Anticlockwise Rotations anywhere in the Universe propelling the spacecraft radially (Hyperspace coordinates that is) away from Orion's Belt-which is approximately 300 or so light years away. For the Prospective investor in antigravity technology and its numerous applications inclusive of gravitational wave propulsion you R&D department will have more than enough information with my works on Academia.edu; particularly this paper being introduced and material aspects of the Biefeld-Brown Effect Of Antigravity, Solid State Star Gate Projector, Metaphysics, A History of Antigravity Research and the Semi-Numerical Witwatersrand Approximation Method 2. Commercially Available texts that I would recommend for your R&D departments would be Theory Of Everything TOE by Fran De Aquino Of Brasil (copyright 2010 A.D. or there about) as well as Beyond The Visible Universe by Stoyan Sarg and his earlier publication Basic Structure Of Matter BSM Theory and Technology Of The Gods: The Incredible Technology Of The Ancients & The Antigravity Files by David Hatcher Childress; & a paper from 2013 A.D. by L.L. Williams Electromagnetic Control Of Gravity: The Hard Problem Of Interstellar Travel Manitou Springs Colarado U.S.A. This should be enough information & knowledge for the Space Age (which it seems has been around before Adam & Eve!).

We calculated the expected neutrino signal in Borexino from a typical Type II supernova at a distance of 10 kpc. A burst of around 110 events would appear in Borexino within a time interval of about 10 s. Most of these events would come from the reaction channelν e + p → e + + n, while about 30 events would be induced by the interaction of the supernova neutrino flux on 12 C in the liquid scintillator. Borexino can clearly distinguish between the neutral-current excitations 12 C(ν, ν ′) 12 C * (15.11 MeV) and the charged-current reactions 12 C(ν e , e −) 12 N and 12 C(ν e , e +) 12 B, via their distinctive event signatures. The ratio of the chargedcurrent to neutral-current neutrino event rates and their time profiles with respect to each other can provide a handle on supernova and non-standard neutrino physics (mass and flavor oscillations).

Any Geiger counter is itself a good cosmic ray detector, indeed is it known that even without the presence of radioactive elements the instrument has the movement of the needle that therefore measures a certain activity called background radiation: more then 11% of this background activity is due to the cosmic radiation, however the rest of the radiation comes from the ground or from the air. To exclude the latter, is needed the so called coincident circuit invented by Bothe and Rossi in the early '30. AMD5 stands for Astroparticle Muon Detector and is a reliable cosmic ray detector built with GMT tubes and a very simple electronic circuit.

Although high-energy astrophysical neutrinos were discovered in 2013, their origin is still unknown. Aiming for the identification of an electromagnetic counterpart of a rapidly fading source, we have implemented a realtime analysis framework for the IceCube neutrino observatory. Several analyses selecting neutrinos of astrophysical origin are now operating in realtime at the detector site in Antarctica and are producing alerts for the community to enable rapid follow-up observations. The goal of these observations is to locate the astrophysical objects responsible for these neutrino signals. This paper highlights the infrastructure in place both at the South Pole site and at IceCube facilities in the north that have enabled this fast follow-up program to be implemented. Additionally, this paper presents the first realtime analyses to be activated within this framework, highlights their sensitivities to astrophysical neutrinos and background event rates, and presents an outlook for future discoveries.

SS433, located at the center of the supernova remnant W50, is a close proximity binary system consisting of a compact star and a normal star. Jets of material are directed outwards from the vicinity of the compact star symmetrically to the east and west. Non-thermal hard X-ray emission is detected from lobes lying on both sides. Shock accelerated electrons are expected to generate VHE gamma rays through the inverse-Compton process in the lobes. Observations of the western X-ray lobe region of SS433/W50 system have been performed to detect VHE gamma rays using the 10 m CANGAROO-II telescope in August and September, 2001, and July and September, 2002. The total observation times are 85.2 h for ON source, and 80.8 h for OFF source data. No significant excess of VHE gamma rays has been found at three regions of the western X-ray lobe of SS433/W50 system. We have derived 99% confidence level upper limits to the fluxes of gamma rays and have set constraints on the strengths of the magnetic fields assuming the synchrotron/inverse-Compton model for the wide energy range of photon spectrum from radio to TeV. The derived lower limits are 4.3 µG for the center of the brightest X-ray emission region and 6.3 µG for the far end from SS433 in the western X-ray lobe. In addition, we suggest that the spot-like X-ray emission may provide a major contribution to the hardest X-ray spectrum in the lobe.

We present a measurement of the cosmic ray e+ + e- flux in the range 0.5 GeV to 1 TeV based on the analysis of 10.6 million e+ + e- events collected by AMS. The statistics and the resolution of AMS provide a precision measurement of the flux. The flux is smooth and reveals new and distinct information. Above 30.2 GeV, the flux can be described by a single power law with a spectral index
γ = −3.170 +- 0.008 (stat þ syst) +- 0.008 (energy scale).

We present evidence for a dependence of the average deep underground muon energies on shower size in the coincident EAS-TOP and LVD data at the Gran Sasso laboratories. The measured relation agrees with a mixed chemical composition of the cosmic ray primary spectrum at energies around 10L5 eV.

Cosmological and astrophysical measurements provide powerful constraints on neutrino masses complementary to those from accelerators and reactors. Here we provide a guide to these different probes, for each explaining its physical basis, underlying assumptions, current and future reach.

Precision cosmological measurements push the boundaries of our understanding of the fundamental physics that governs our universe. In the coming years, cosmologists will be in a position to make major breakthroughs in our understanding of the physics of the very early universe and be able to probe particle physics and gravity at the highest energy scales yet accessed. A major leap forward in the sensitivity of cosmological experiments is within our technological reach, leveraging past and current experience to tackle some of the most interesting fundamental physics questions.

An upper limit to the flux of Ultra High Energy (UHE) y-rays in the primary cosmic radiation is obtained through the data of the electromagnetic and the muon detectors of the EAS-TOP Extensive Air Shower array (Camp0 Imperatore, National Gran Sasso Laboratories, atmospheric depth 810gcm-*).

Generally, the dynamics of test particles around galaxies, as well as the corresponding mass deficit, is explained by postulating the existence of a hypothetical dark matter. In fact, the behavior of the rotation curves shows the existence of a constant velocity region, near the baryonic matter distribution, followed by a quick decay at large distances. In this work, we consider the possibility that the behavior of the rotational velocities of test particles gravitating around galaxies can be explained within the framework of the recently proposed hybrid metric-Palatini gravitational theory. The latter is constructed by modifying the metric Einstein-Hilbert action with an f (R) term in the Palatini formalism. It was shown that the theory unifies local constraints and the late-time cosmic acceleration, even if the scalar field is very light. In the intermediate galactic scale, we show explicitly that in the hybrid metric-Palatini model the tangential velocity can be explicitly obtained as a function of the scalar field of the equivalent scalar-tensor description. The model predictions are compared model with a small sample of rotation curves of low surface brightness galaxies, respectively, and a good agreement between the theoretical rotation curves and the observational data is found. The possibility of constraining the form of the scalar field and the parameters of the model by using the stellar velocity dispersions is also analyzed. Furthermore, the Doppler velocity shifts are also obtained in terms of the scalar field. All the physical and geometrical quantities and the numerical parameters in the hybrid metric-Palatini model can be expressed in terms of observable/measurable parameters, such as the tangential velocity, the baryonic mass of the galaxy, the Doppler frequency shifts, and the stellar dispersion velocity, respectively. Therefore, the obtained results open the possibility of testing the hybrid metric-Palatini gravitational models at the galactic or extra-galactic scale by using direct astronomical and astrophysical observations.

We consider the behavior of the tangential velocity of test particles moving in stable circular orbits in f (R) modified theories of gravity. A large number of observations at the galactic scale have shown that the rotational velocities of massive test particles (hydrogen clouds) tend towards constant values at large distances from the galactic center. We analyze the vacuum gravitational field equations in f (R) models in the constant velocity region, and the general form of the metric tensor is derived in a closed form. The resulting modification of the Einstein-Hilbert Lagrangian is of the form R 1+n , with the parameter n expressed in terms of the tangential velocity. Therefore we find that to explain the motion of test particles around galaxies requires only very mild deviations from classical general relativity, and that modified gravity can explain the galactic dynamics without the need of introducing dark matter.

We present results from a fully relativistic Monte Carlo simulation of diffusive shock acceleration (DSA) in unmodified shocks. The computer code uses a single algorithmic sequence to smoothly span the range from non-relativistic speeds to fully relativistic shocks of arbitrary obliquity, providing a powerful consistency check. While known results are obtained for non-relativistic and ultra-relativistic parallel shocks, new results are presented for the less explored trans-relativistic regime and for oblique, fully relativistic shocks. We find, for a wide trans-relativistic range extending to shock Lorentz factors >30, that the particle spectrum produced by DSA varies strongly from the canonical f(p) / p À4.23 spectrum known to result in ultra-relativistic shocks. Trans-relativistic shocks may play an important role in c-ray bursts and other sources and most relativistic shocks will be highly oblique.

A basic paradigm of physics is that if one measures the distance to an object as a function of time, one can determine the velocity and acceleration. Add dynamics and one can find the forces, either from F = ma or G µν = 8πT µν , and from these one can determine the nature of the underlying matter. Already, distance measurements have shown that the cosmological constant, long disowned as being no more than theoretically allowable, is, in fact, a necessity, now recast in the form of dark energy. Plot distance as a function of time to determine the forces. What remains to be seen is whether the Universe is pervaded by a uniform and never-changing energy density or by something akin to, but varying in time and perhaps position. Or whether describing the Universe as a whole by General Relativity fails. Whatever future experiments reveal, the simple plot of the distance scale of the Universe as a function of time will be one of the primary icons of physical science. As the Copernican picture of the solar system placed us away from the center, the cosmological distance plot will show the minority position of our sort of matter in the cosmos.

We have designed and built an instrument to measure and monitor the ''nightglow'' of the EarthÕs atmosphere in the near ultraviolet (NUV). In this paper we describe the design of this instrument, called NIGHTGLOW. NIGHTGLOW is designed to be flown from a high altitude research balloon, and circumnavigate the globe. NIGHTGLOW is a NASA, University of Utah, and New Mexico State University project. A test flight took place from Palestine, Texas on July 5, 2000, lasting about 8 h. The instrument performed well and landed safely in Stiles, Texas with little damage. The resulting measurements of the NUV nightglow are compared with previous measurements from sounding rockets and balloons. Published by Elsevier B.V. PACS: 95.30.Àk; 95.55.Àn; 96.40.Àz

The Cherenkov radio pulse emitted by hadronic showers in ice is calculated for showers of energies in the EeV range. This is obtained with three dimensional simulations of both shower development and the coherent radio pulse emitted as the excess charge develops in the shower. A Monte Carlo, ZHAIRE S , has been developed for this purpose combining the high energy hadronic interaction capabilities of AIRES, and the dense media propagation capabilities of TIERRAS, with the precise low energy tracking and specific algorithms developed to calculate the radio emission in ZHS. A thinning technique is implemented and optimized to allow the simulation of radio pulses induced by showers up to 10 EeV in ice. The code is validated comparing the results for electromagnetic and hadronic showers to those obtained with GEANT4 and ZHS codes. The contribution to the pulse of other shower particles in addition to electrons and positrons, mainly pions and muons, is found to be below 1 %. The characteristics of hadronic showers and the corresponding Cherenkov frequency spectra are compared with those from purely electromagnetic showers. The dependence of the spectra on shower energy and high-energy hadronic model is addressed and parameterizations for the radio emission in hadronic showers in ice are given for practical applications.

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 (N l ) and shower size (N e ) 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 E He k ¼ ð3:5 AE 0:3Þ Â 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 E 0 % 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 (c p;He > 3:1), (ii) a spectrum of the intermediate mass group harder than the one of the light component (c CNO ' 2:75, possibly bending at E heavy primaries (c Fe ' 2:3-2:7) consistent with the direct measurements. In the investigated energy range, the average primary mass increases from hln Ai ¼ 1:6-1:9 at E 0 ' 1:5 Â 10 6 GeV to hln Ai ¼ 2:8-3:1 at E 0 ' 1:5 Â 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.

Recent data on Galactic cosmic rays (CRs) revealed that the helium energy spectrum is harder than the proton spectrum. The AMS experiment has now reported that the proton-to-helium ratio as function of rigidity R (momentum-to-charge ratio) falls off steadily as p/He∝ R∆, with ∆ ≈ −0.08 between R ∼40GV and R ∼2TV. Besides, the single spectra of proton and helium are found to progressively harden at R 􏰀100GV. The p/He anomaly is generally ascribed to particle- dependent acceleration mechanisms occurring in Galactic CR sources. However, this explanation poses a challenge to the known mechanisms of particle acceleration since they are believed to be “universal”, composition blind, rigidity mechanisms. Using the new AMS data, we show that the p/He anomaly can be simply explained in terms of a two-component scenario where the GeV–TeV flux is ascribed to a hydrogen-rich source, possibly a nearby supernova remnant, characterized by a soft acceleration spectrum. This simple idea provides a common interpretation for the p/He ratio and for the single spectra of proton and helium: both anomalies are explained by a flux transition between two components. The “universality” of particle acceleration in sources is not violated in this model. A distinctive signature of our scenario is the high-energy flattening of the p/He ratio at multi-TeV energies, which is hinted at by existing data and will be resolutely tested by new space experiments ISS-CREAM and CALET.

Looking at the data of cosmic rays obtained by the neutron detector of the Sphinx (IGY NM
Jungfraujoch - JUNG) [1,3], and comparing them to the data of glaciers at a global level and
also at local level (WGMS 2012, updated and earlier issues) [2] it is evident that follow the
same trend. At a glance this may not prove a direct link between cosmic rays and climate, but a
more close observation can provide additional support to recent cosmo-climatological theories.

Air shower simulation programs are essential tools for the analysis of data from cosmic ray experiments and for planning the layout of new detectors. They are used to estimate the energy and mass of the primary particle. Unfortunately the model uncertainties translate directly into systematic errors in the energy and mass determination. Aiming at energies > 10 19 eV, the models have to be extrapolated far beyond the energies available at accelerators. On the other hand, hybrid measurement of ground particle densities and calorimetric shower energy, as will be provided by the Pierre Auger Observatory, will strongly constrain shower models. While the main uncertainty of contemporary models comes from our poor knowledge of the (soft) hadronic interactions at high energies, also electromagnetic interactions, low-energy hadronic interactions and the particle transport influence details of the shower development. We review here the physics processes and some of the computational techniques of air shower models presently used for highest energies, and discuss the properties and limitations of the models.

The Very Energetic Radiation Imaging Telescope Array System (VERITAS) represents an important step forward in the study of extreme astrophysical processes in the universe. It combines the power of the atmospheric Cherenkov imaging technique using a large optical reflector ...

A large area (128 m 2) muon tracking detector, located within the KASCADE experiment, has been built with the aim to identify muons (E µ > 0.8 GeV) and their angular correlation in extensive air showers by track measurements under 18 r.l. shielding. Orientation of the muon track with respect to the shower axis is expressed in terms of the radial and tangential angles, which are the basic tools for all muon investigations with the tracking detector. By means of triangulation the muon production height is determined. Distributions of measured production heights are compared to CORSIKA shower simulations. Analysis of these heights reveals a transition from light to heavy cosmic ray primary particles with increasing shower energy in the energy region of the 'Knee' of the cosmic ray spectrum.

Local interstellar spectra (LIS) for protons, helium and antiprotons are built using the most recent experimental results combined with the state-of-the-art models for propagation in the Galaxy and heliosphere. Two propagation packages, GALPROP and HelMod, are combined to provide a single framework that is run to reproduce direct measurements of cosmic ray (CR) species at different modulation levels and at both polarities of the solar magnetic field. To do so in a self-consistent way, an iterative procedure was developed, where the GALPROP LIS output is fed into HelMod that provides modulated spectra for specific time periods of selected experiments to compare with the data; the HelMod parameters optimization is performed at this stage and looped back to adjust the LIS using the new GALPROP run. The parameters were tuned with the maximum likelihood procedure using an extensive data set of proton spectra from 1997–2015. The proposed LIS accommodate both the low energy interstellar CR spectra measured by Voyager 1 and the high energy observations by BESS, Pamela, AMS-01, and AMS-02 made from the balloons and near-Earth payloads; it also accounts for Ulysses counting rate features measured out of the ecliptic plane. The found solution is in a good agreement with proton, helium, and antiproton data by AMS-02, BESS, and PAMELA in the whole energy range.

he cosmological background of gravitational waves can be tuned by the higher-order corrections to the gravitational Lagrangian. In particular, it can be shown that assuming $R^{1+\epsilon}$, where $\epsilon$ indicates a generic (eventually small) correction to the Hilbert-Einstein action in the Ricci scalar $R$, gives a parametric approach to control the evolution and the production mechanism of gravitational waves in the early Universe.

A method and results of an experimental test of the time stability of the half-life of alpha-decay 214 Po nuclei are presented. Two underground installations aimed at monitoring the time stability have been constructed. Time of measurement exceeds 1038 days for one set up and 562 days for the other. It was found that amplitude of possible annual variation of 214 Po half-life does not exceed 0.2% of the mean value. The limit on the deviation of the decay curve from exponent at 0.034 · T 1/2 < t < 0.1 · T 1/2 range has been found.

Precision measurements of cosmic ray positrons are presented up to 1 TeV based on 1.9 million positrons collected by the Alpha Magnetic Spectrometer on the International Space Station. The positron flux exhibits complex energy dependence. Its distinctive properties are (a) a significant excess starting from 25.2±1.8  GeV compared to the lower-energy, power-law trend, (b) a sharp dropoff above 284+91−64  GeV, (c) in the entire energy range the positron flux is well described by the sum of a term associated with the positrons produced in the collision of cosmic rays, which dominates at low energies, and a new source term of positrons, which dominates at high energies, and (d) a finite energy cutoff of the source term of Es=810+310−180  GeV is established with a significance of more than 4σ. These experimental data on cosmic ray positrons show that, at high energies, they predominantly originate either from dark matter annihilation or from other astrophysical sources.

Ultra-high energy cosmic rays (UHECRs) may originate from the decay of massive relic particles in the dark halo of the Galaxy, or they may be produced in nearby galaxies, for example by supermassive black holes in their nuclei. The anisotropy in the arrival directions is studied in four dark halo models (cusped, isothermal, triaxial and tilted) and in four galaxy samples (galaxies intrinsically brighter than Centaurus A within 50 and 100 Mpc, and galaxies intrinsically brighter than M32 within 50 and 100 Mpc).