Search

Our latest paper (Dolgikh et al., 2023) investigates the effects of UHECR propagation in a turbulent intergalactic magnetic field in the small-angle scattering regime, specifically focusing on the non-trivial caustic-like pattern that arises with strong deviation from isotropy. In this paper, we explore the effect of the observer's position on the measurement of source flux at a given distance. We examine three types of source locations, characterized by the density of cosmic rays from a given source at the observation point, which we call magnetic knots, magnetic filaments and magnetic voids. We also investigate the energy spectrum in these different cases and present simulated images of the source as it appears on the observer's telescope after propagation in the combination of intergalactic and Galactic magnetic fields. We show that hot spots in the UHECR data can arrive due to combined distortions of the source images on the intergalactic and Galactic magnetic fields. Also the fact that flux of most nearby sources is diluted in the magnetic voids affects source population studies. [ABSTRACT FROM AUTHOR]

The main goal of the TUS experiment was to search for and study ultra high-energy cosmic rays with energies E > 70 EeV. At the same time, the TUS detector registered a number of unusual events, the origin of which was unclear. Events that are unique and not similar to EAS are the subject of the study presented in this paper. Events such as gamma-ray bursts (GRBs), out-of-aperture upward going EASs accompanied by lightning flashes, as well as terrestrial gamma-ray flashes (TGFs) are considered as their possible sources. [ABSTRACT FROM AUTHOR]

The ultra-high-energy cosmic ray (UHECR) puzzle is reviewed under the hints of a few basic results: clustering, anisotropy, asymmetry, bending, and composition changes with energies. We show how the lightest UHECR nuclei from the nearest AGN or Star-Burst sources, located inside a few Mpc Local Sheets, may explain, at best, the observed clustering of Hot Spots at tens EeV energy. Among the possible local extragalactic candidate sources, we derived the main contribution of very few galactic sources. These are located in the Local Sheet plane within a distance of a few Mpc, ejecting UHECR at a few tens of EeV energy. UHECR also shine at lower energies of several EeV, partially feeding the Auger dipole by LMC and possibly a few nearer galactic sources. For the very recent highest energy UHECR event, if a nucleon, it may be explained by a model based on the scattering of UHE ZeV neutrinos on low-mass relic neutrinos. Such scatterings are capable of correlating, via Z boson resonance, the most distant cosmic sources above the GZK bound with such an enigmatic UHECR event. Otherwise, these extreme events, if made by the heaviest composition, could originate from the largest bending trajectory of heaviest nuclei or from nearby sources, even galactic ones. In summary, the present lightest to heavy nuclei model UHECR from the Local Sheet could successfully correlate UHECR clustering with the nearest galaxies and AGN. Heavy UHECR may shine by being widely deflected from the Local Sheet or from past galactic, GRB, or SGR explosive ejection. [ABSTRACT FROM AUTHOR]

NUSES is a pathfinder satellite project hosting two detectors: Ziré and Terzina. Ziré focuses on the study of protons and electrons below 250 MeV and MeV gamma rays. Terzina is dedicated to the detection of Cherenkov light produced by ultra-high-energy cosmic rays above 100 PeV and ultra-high-energy Earth-skimming neutrinos in the atmosphere, ensuring a large exposure. This work mainly concerns the description of the Cherenkov camera, composed of SiPMs, for the Terzina telescope. To increase the data-taking period, the NUSES orbit will be Sun-synchronous (with a height of about 550 km), thus allowing Terzina to always point toward the dark side of the Earth's limb. The Sun-synchronous orbit requires small distances to the poles, and as a consequence, we expect an elevated dose to be received by the SiPMs. Background rates due to the dose accumulated by the SiPM would become a dominant contribution during the last two years of the NUSES mission. In this paper, we illustrate the measured effect of irradiance on SiPM photosensors with a variable-intensity beam of 50 MeV protons up to a 30 Gy total integrated dose. We also show the results of an initial study conducted without considering the contribution of solar wind protons and with an initial geometry with Geant4. The considered geometry included an entrance lens as one of the options in the initial design of the telescope. We characterize the SiPM output signal shape with different μ-cell sizes. We describe the developed parametric SiPM simulation, which is a part of the full Terzina simulation chain. [ABSTRACT FROM AUTHOR]

The ultra-high-energy cosmic ray (UHECR) puzzle is reviewed under the hints of a few basic results: clustering, anisotropy, asymmetry, bending, and composition changes with energies. We show how the lightest UHECR nuclei from the nearest AGN or Star-Burst sources, located inside a few Mpc Local Sheets, may explain, at best, the observed clustering of Hot Spots at tens EeV energy. Among the possible local extragalactic candidate sources, we derived the main contribution of very few galactic sources. These are located in the Local Sheet plane within a distance of a few Mpc, ejecting UHECR at a few tens of EeV energy. UHECR also shine at lower energies of several EeV, partially feeding the Auger dipole by LMC and possibly a few nearer galactic sources. For the very recent highest energy UHECR event, if a nucleon, it may be explained by a model based on the scattering of UHE ZeV neutrinos on low-mass relic neutrinos. Such scatterings are capable of correlating, via Z boson resonance, the most distant cosmic sources above the GZK bound with such an enigmatic UHECR event. Otherwise, these extreme events, if made by the heaviest composition, could originate from the largest bending trajectory of heaviest nuclei or from nearby sources, even galactic ones. In summary, the present lightest to heavy nuclei model UHECR from the Local Sheet could successfully correlate UHECR clustering with the nearest galaxies and AGN. Heavy UHECR may shine by being widely deflected from the Local Sheet or from past galactic, GRB, or SGR explosive ejection.

NUSES is a pathfinder satellite project hosting two detectors: Ziré and Terzina. Ziré focuses on the study of protons and electrons below 250 MeV and MeV gamma rays. Terzina is dedicated to the detection of Cherenkov light produced by ultra-high-energy cosmic rays above 100 PeV and ultra-high-energy Earth-skimming neutrinos in the atmosphere, ensuring a large exposure. This work mainly concerns the description of the Cherenkov camera, composed of SiPMs, for the Terzina telescope. To increase the data-taking period, the NUSES orbit will be Sun-synchronous (with a height of about 550 km), thus allowing Terzina to always point toward the dark side of the Earth’s limb. The Sun-synchronous orbit requires small distances to the poles, and as a consequence, we expect an elevated dose to be received by the SiPMs. Background rates due to the dose accumulated by the SiPM would become a dominant contribution during the last two years of the NUSES mission. In this paper, we illustrate the measured effect of irradiance on SiPM photosensors with a variable-intensity beam of 50 MeV protons up to a 30 Gy total integrated dose. We also show the results of an initial study conducted without considering the contribution of solar wind protons and with an initial geometry with Geant4. The considered geometry included an entrance lens as one of the options in the initial design of the telescope. We characterize the SiPM output signal shape with different μ-cell sizes. We describe the developed parametric SiPM simulation, which is a part of the full Terzina simulation chain.

Compelling evidence for Lorentz invariance violation (LIV) would demand a complete revision of modern physics. Therefore, searching for a signal or extending the validity of the invariance is fundamental for building our understanding of the extreme phenomena in the Universe. In this paper, we review the potential of ultra-high-energy astroparticles in setting limits on LIV. The standard framework of LIV studies in astroparticle physics is reviewed and its use on the electromagnetic and hadronic sectors are discussed. In particular, the current status of LIV tests using experimental data on ultra-high-energy photons and cosmic rays is addressed. A detailed discussion with improved argumentation about the LIV kinematics of the relevant interactions is shown. The main previous results are presented together with new calculations based on recently published astrophysical models. [ABSTRACT FROM AUTHOR]

Here, we point out that an observation of ultrahigh energy cosmic ray (UHECR) photons, "GZK photons", could provide an upper limit on the level of the extragalactic radio background, depending on the level of UHECR proton primaries (to be determined after a few years of data taking by the Pierre Auger Observatory upgrade AugerPrime). We also update our 2005 prediction of the range of GZK photon fluxes expected from proton primaries. [ABSTRACT FROM AUTHOR]

Rotating black holes (BHs) are likely the largest energy reservoirs in the Universe as predicted by BH thermodynamics, while cosmic rays (CRs) are the most energetic among particles detected on Earth. Magnetic fields surrounding BHs combined with strong gravity effects, thanks to the spacetime symmetries, turn the BHs into powerful accelerators of charged particles. At the same time, in the age of multi-wavelength and multi-messenger astronomy, BHs and their environments have not yet been probed with CR messengers, despite being observed across most of the electromagnetic spectrum, and neutrino and gravitational waves. In this paper, we probe the acceleration capabilities of BHs in 8 galactic X-ray binaries and 25 local active galactic nuclei (AGNs) within 100 Mpc, based on the ultra-efficient regime of the magnetic Penrose process of a BH energy extraction combined with observational data. We find that the maximum energy of the galactic BHs can reach only up to the knee of the CR spectrum, including supermassive BH Sgr A* at the Galactic Center. On the other hand, for supermassive BHs in AGNs, we find that the mean energy of primary CRs is of the order of 10 19 eV. It is therefore likely that local supermassive BHs give sufficient contribution to the ankle—a sharp change in the slope of the cosmic ray spectrum around 10 18.6 eV energy. We also discuss the energy losses of primary CRs close to the acceleration zones. In the galactic BH cases, it is likely dominated by synchrotron radiation losses. [ABSTRACT FROM AUTHOR]

A scientific instrument comprised of a global network of millions of independent, connected, remote devices presents unique data acquisition challenges. We describe the software design of a mobile application which collects data from smartphone cameras without overburdening the phone's CPU or battery. The deployed software automatically calibrates to heterogeneous hardware targets to improve the quality and manage the rate of data transfer, and connects to a cloud-based data acquisition system which can manage and refine the operation of the network. [ABSTRACT FROM AUTHOR]

Several experiments around the world, like the ground-based observatories Pierre Auger and Telescope Array, and soon the space telescope JEM-EUSO, are investigating ultra-high-energy cosmic rays, trying to solve the mystery of their origin. The mass composition of these particles is a key piece of information crucial for a better understanding of the problem. Yet it cannot be observed directly but rather inferred from the simultaneous measure of the energy E 0 of the primary particle and the atmospheric depth X max of its shower maximum. The conversion of ( E 0 , X max ) into a primary mass can only be achieved by air-shower simulation. The paper investigates this question through detailed Monte Carlo calculations of air showers initiated by ultra-high-energy cosmic rays of 10 18 – 10 20 eV. The calculations were carried out using the code CONEX in combination with different up-to-date hadronic interaction models. The obtained results are compared to the most recent data from the current experiments. [ABSTRACT FROM AUTHOR]

Compelling evidence for Lorentz invariance violation (LIV) would demand a complete revision of modern physics. Therefore, searching for a signal or extending the validity of the invariance is fundamental for building our understanding of the extreme phenomena in the Universe. In this paper, we review the potential of ultra-high-energy astroparticles in setting limits on LIV. The standard framework of LIV studies in astroparticle physics is reviewed and its use on the electromagnetic and hadronic sectors are discussed. In particular, the current status of LIV tests using experimental data on ultra-high-energy photons and cosmic rays is addressed. A detailed discussion with improved argumentation about the LIV kinematics of the relevant interactions is shown. The main previous results are presented together with new calculations based on recently published astrophysical models.

Here, we point out that an observation of ultrahigh energy cosmic ray (UHECR) photons, “GZK photons”, could provide an upper limit on the level of the extragalactic radio background, depending on the level of UHECR proton primaries (to be determined after a few years of data taking by the Pierre Auger Observatory upgrade AugerPrime). We also update our 2005 prediction of the range of GZK photon fluxes expected from proton primaries.

Rotating black holes (BHs) are likely the largest energy reservoirs in the Universe as predicted by BH thermodynamics, while cosmic rays (CRs) are the most energetic among particles detected on Earth. Magnetic fields surrounding BHs combined with strong gravity effects, thanks to the spacetime symmetries, turn the BHs into powerful accelerators of charged particles. At the same time, in the age of multi-wavelength and multi-messenger astronomy, BHs and their environments have not yet been probed with CR messengers, despite being observed across most of the electromagnetic spectrum, and neutrino and gravitational waves. In this paper, we probe the acceleration capabilities of BHs in 8 galactic X-ray binaries and 25 local active galactic nuclei (AGNs) within 100 Mpc, based on the ultra-efficient regime of the magnetic Penrose process of a BH energy extraction combined with observational data. We find that the maximum energy of the galactic BHs can reach only up to the knee of the CR spectrum, including supermassive BH Sgr A* at the Galactic Center. On the other hand, for supermassive BHs in AGNs, we find that the mean energy of primary CRs is of the order of 1019 eV. It is therefore likely that local supermassive BHs give sufficient contribution to the ankle—a sharp change in the slope of the cosmic ray spectrum around 1018.6 eV energy. We also discuss the energy losses of primary CRs close to the acceleration zones. In the galactic BH cases, it is likely dominated by synchrotron radiation losses.

An overview of the multi-messenger capabilities of the Pierre Auger Observatory is presented. The techniques and performance of searching for Ultra-High Energy neutrinos, photons and neutrons are described. Some of the most relevant results are reviewed, such as stringent upper bounds that were placed to a flux of diffuse cosmogenic neutrinos and photons, bounds placed on neutrinos emitted from compact binary mergers that were detected by LIGO and Virgo during their first and second observing runs, as well as searches for high energy photons and neutrons from the Galactic center that constrain the properties of the putative Galactic PeVatron, observed by the H.E.S.S. collaboration. The observation of directional correlations between ultra-high energy cosmic rays and either high energy astrophysical neutrinos or specific source populations, weighted by their electromagnetic radiation, are also discussed. They constitute additional multi-messenger approaches aimed at identifying the sources of high energy cosmic rays.

Summary In this paper, the flight software architecture of the EUSO‐SPB mission is described. The JEM‐EUSO program aims at developing an advanced large space‐borne UV telescope designed to detect ultra high energy cosmic rays. In this framework, the EUSO‐SPB experiment is the third pathfinder mission of the JEM‐EUSO program, the second that has been launched on a stratospheric balloon to test the technological readiness of the detectors and to carry out some preliminary scientific observations. The EUSO‐SPB software has a modular structure conceived to control all the instruments and the ancillary subsystems, to acquire data, and to manage data transfer to ground. System programming in C and C++ languages and Bash scripts have been used to implement and run the modules. The software runs on the data processor, an onboard computer that communicates with several payload blocks, the UV sensor, and the synchronization and time tagging board. The control software module controls all the subsystems, provides communication to ground through the NASA telemetry or the Internet, runs the acquisition control and download software, and manages the execution of the acquisition software. The acquisition software module directly operates the subsystems for the data acquisition activity. The acquisition control and download software module runs the acquisition software upon request of the control software and transfers scientific data to ground. The software system performed as expected during the flight on April 2017. [ABSTRACT FROM AUTHOR]

The Pierre Auger Observatory is an Ultra-High Energy Cosmic Ray (UHECR) detector which has studied cosmic particles with energies above and around 1018 eV for more than 15 years. It has proved to be the most competitive instrument at these energies and has produced a wealth of valuable results, improving our understanding of UHECRs. A complete understanding of these highest energy particles is crucial to understand the extreme astrophysical events in which they are produced and accelerated, as well as their propagation to Earth. In the same range of energies, UHE photons and neutrinos are of paramount importance as, being electrically neutral, they point back to their origin while charged particles are deflected in the galactic and extragalactic magnetic fields. The flux of extragalactic photons, neutrinos, and cosmic rays are believed to be highly linked, by their origin and their interactions. Each messenger provides different information about the potential sources, and having detection means for all four messengers, including gravitational waves, allows us to shed light on energetic sources of astroparticles. The Pierre Auger Observatory benefits from a large exposure and a good angular resolution, and is efficient in detecting UHE photons and neutrinos. These performances make possible follow-up searches for events detected by gravitational waves, such as the binary mergers observed by the LIGO/Virgo detectors, or any other energetic sources of particles.

EUSO-TA is a ground-based telescope, installed at the Telescope Array (TA) site in Black Rock Mesa, Utah, USA. This is the first detector to successfully use a Fresnel lens based optical system and multi-anode photomultipliers (64 channels per tube, 2304 channels encompassing a 10.6° × 10.6° field of view) for detection of Ultra High Energy Cosmic Rays (UHECR). The telescope is located in front of one of the fluorescence detectors of the TA experiment. Since its installation in 2013, the detector has observed several ultra-high energy cosmic ray events and, in addition, meteors. The limiting magnitude of 5.5 on summed frames ( ∼ 3 ms) has been established. Measurements of the UV night sky emission in different conditions and moon phases and positions have been completed. The performed observations serve as a proof of concept for the future application of this detector technology. [ABSTRACT FROM AUTHOR]

Stochastic acceleration of cosmic rays in second order Fermi processes is usually considered too slow to reach ultra-high energies, except in specific cases. In this paper we present the energy spectrum obtained from second order Fermi acceleration in highly turbulent magnetic fields as e.g. found in the outskirts of AGN jets in situations where it can be sufficiently fast to accelerate particles to the highest observed energies. We parametrize the resulting non-power-law spectra and show that these can describe the cosmic ray energy spectrum and mass-composition data at the highest energies if propagation effects are taken into account. [ABSTRACT FROM AUTHOR]

CORSIKA (COsmic Ray SImulations for Kascade) has various features in the creation of the extensive air showers with several characteristics where the users can configure the input card to achieve the desired result. ECUT is a parameter defined as the low energy cutoff of the particle kinetic energy for hadrons, muons, electrons, and photons. We investigate the effect of the different ECUT values on the detected particles in 107 - 5 × 108 GeV primary particle energy range where π-π0 decay channel chosen with 5 km shower development length. The selected ECUT values in this study are 0.05 and 0.1 GeV for both hadrons and muons and 0.05 GeV for electrons and photons. The effect of the reducing by half on the energy cutoff value is studied for the detector array located on an inclined plane, which is planned for upward τ detection. [ABSTRACT FROM AUTHOR]

We describe a method of reconstructing air showers induced by cosmic rays using deep learning techniques. We simulate an observatory consisting of ground-based particle detectors with fixed locations on a regular grid. The detector’s responses to traversing shower particles are signal amplitudes as a function of time, which provide information on transverse and longitudinal shower properties. In order to take advantage of convolutional network techniques specialized in local pattern recognition, we convert all information to the image-like grid of the detectors. In this way, multiple features, such as arrival times of the first particles and optimized characterizations of time traces, are processed by the network. The reconstruction quality of the cosmic ray arrival direction turns out to be competitive with an analytic reconstruction algorithm. The reconstructed shower direction, energy and shower depth show the expected improvement in resolution for higher cosmic ray energy. [ABSTRACT FROM AUTHOR]

The reconstruction of cosmic-ray-induced extensive air showers with a non-imaging Cherenkov detector array requires knowledge of the Cherenkov yield of any given air shower for a given set of shower parameters. Although air showers develop in a stochastic cascade, certain characteristics of the particles in the shower have been shown to come from universal probability distributions, a property known as shower universality. Both the energy and the angular distributions of charged particles within a shower have been parameterized. One can use these distributions to calculate the Cherenkov photon yield as an angular distribution from the Cherenkov cones of charged particles at various stages of shower development. This Cherenkov photon yield can then be tabulated for use in the reconstruction of air showers. In this work, we develop the calculation of both the Cherenkov angular distribution and Cherenkov yield per shower particle, and show how a look-up table was constructed to capture the relevant features of these distributions for general use. We compare the results of our calculations with the results of full, particle-stack, Monte Carlo simulation of the Cherenkov light produced in extensive air showers using CORSIKA-IACT. We make comparisons of both the lateral distribution of the Cherenkov photon flux amongst several detectors and of the arrival-time distribution of the Cherenkov photons in a single detector. [ABSTRACT FROM AUTHOR]

Magnetic Penrose process (MPP) is not only the most exciting and fascinating process mining the rotational energy of black hole but it is also the favored astrophysically viable mechanism for high energy sources and phenomena. It operates in three regimes of efficiency, namely low, moderate and ultra, depending on the magnetization and charging of spinning black holes in astrophysical setting. In this paper, we revisit MPP with a comprehensive discussion of its physics in different regimes, and compare its operation with other competing mechanisms. We show that MPP could in principle foot the bill for powering engine of such phenomena as ultra-high-energy cosmic rays, relativistic jets, fast radio bursts, quasars, AGNs, etc. Further, it also leads to a number of important observable predictions. All this beautifully bears out the promise of a new vista of energy powerhouse heralded by Roger Penrose half a century ago through this process, and it has today risen in its magnetically empowered version of mid 1980s from a purely thought experiment of academic interest to a realistic powering mechanism for various high-energy astrophysical phenomena.

The TUS space experiment is aimed at studying energy and arrival distribution of UHECR at E > 7 × 10 19 eV by using the data of EAS fluorescent radiation in atmosphere. The TUS mission was launched at the end of April 2016 on board the dedicated “Lomonosov” satellite. The TUSSIM software package has been developed to simulate performance of the TUS detector for the Fresnel mirror optical parameters, the light concentrator of the photo detector, the front end and trigger electronics. Trigger efficiency crucially depends on the background level which varies in a wide range: from 0.2 × 10 6 to 15 × 10 6 ph/( m 2 μ s sr) at moonless and full moon nights respectively. The TUSSIM algorithms are described and the expected TUS statistics is presented for 5 years of data collection from the 500 km solar-synchronized orbit with allowance for the variability of the background light intensity during the space flight. [ABSTRACT FROM AUTHOR]

The expected signal in extensive air shower (EAS) detectors can be predicted with a 10% accuracy by a parameterization that depends on a set of global shower parameters: the energy, the depth of the electromagnetic shower maximum ( X max ) and the overall muon content. By classifying shower particles in four components (muonic, purely electromagnetic, electromagnetic stemming from muon interactions and decay and electromagnetic-from-low-energy hadrons), shower-to-shower fluctuations are minimized. We follow this scheme to propose a model to describe the arrival time distributions of secondary particles as measured with surface detectors in an EAS experiment. This model is then used to reconstruct X max in Monte Carlo data sets. As an example, we show that for the case of the Pierre Auger Observatory X max can be reconstructed with an accuracy of about 45 g/cm 2 at 10 19 eV. [ABSTRACT FROM AUTHOR]

The number as well as the energy and angular distributions of particles in extensive air showers (EAS) depend on the stage of the shower development and the distance to the shower axis. In this work we derive an analytic parameterization of the particle distributions at ground from air shower simulations convolved with the response of a surface detector array. Shower particles are classified into four components according to the shower component they belong to: the muonic component, the electromagnetic component stemming from muon interactions and muon decay, the purely electromagnetic component, and the newly introduced electromagnetic component from low-energy hadrons. Using this scheme, we will show that the total signal at ground level for different surface detectors can be described with minimal fluctuations with parameterizations depending on the primary energy, position of the shower maximum, and the overall number of muons in the shower. The simulation results for different combinations of primaries and hadronic interaction models are reproduced with an accuracy better than 5–10% in the range from 100 m to 2000 m from the shower core. This parameterization is then used as a Lateral Distribution ansatz to reconstruct showers in current EAS experiments. Since this ansatz depends on physical parameters, it opens the possibility to infer them from data. [ABSTRACT FROM AUTHOR]

We report the use of an electron light source (ELS) located at the Telescope Array Observatory in Utah, USA, to measure the isotropic microwave radiation from air showers. To simulate extensive air showers, the ELS emits an electron beam into the atmosphere and a parabola antenna system for the satellite communication is used to measure the microwave radiation from the electron beam. Based on this measurement, an upper limit on the intensity of a 12.5 GHz microwave radiation at 0.5 m from a 10 18 eV air shower was estimated to be 3.96×10 −16 W m −2 Hz −1 with a 95% confidence level. [ABSTRACT FROM AUTHOR]

We consider an array of scintillation detectors combined with an array of water Cherenkov detectors designed to simultaneously measure the cosmic-ray primary mass composition and energy spectrum at energies around 1EeV. In this work we investigate the sensitivity to primary mass composition of such combined arrays. The water Cherenkov detectors are arranged in a triangular grid with fixed 750m spacing and the configuration of the scintillation detectors is changed to study the impact of different configurations on the sensitivity to mass composition. We show that the performance for composition determination can be compared favorably to that of fluorescence measurements after the difference in duty cycles is considered. [ABSTRACT FROM AUTHOR]

In this paper we describe the main characteristics of the JEM-EUSO instrument. The Extreme Universe Space Observatory on the Japanese Experiment Module (JEM-EUSO) of the International Space Station (ISS) will observe Ultra High-Energy Cosmic Rays (UHECR) from space. It will detect UV-light of Extensive Air Showers (EAS) produced by UHECRs traversing the Earth's atmosphere. For each event, the detector will determine the energy, arrival direction and the type of the primary particle. The advantage of a space-borne detector resides in the large field of view, using a target volume of about 10 tons of atmosphere, far greater than what is achievable from ground. Another advantage is a nearly uniform sampling of the whole celestial sphere. The corresponding increase in statistics will help to clarify the origin and sources of UHECRs and characterize the environment traversed during their production and propagation. JEM-EUSO is a 1.1 ton refractor telescope using an optics of 2.5 m diameter Fresnel lenses to focus the UV-light from EAS on a focal surface composed of about 5,000 multi-anode photomultipliers, for a total of ≃3⋅10 channels. A multi-layer parallel architecture handles front-end acquisition, selecting and storing valid triggers. Each processing level filters the events with increasingly complex algorithms using FPGAs and DSPs to reject spurious events and reduce the data rate to a value compatible with downlink constraints. [ABSTRACT FROM AUTHOR]

EUSO-Balloon is a pathfinder for JEM-EUSO, the Extreme Universe Space Observatory which is to be hosted on-board the International Space Station. As JEM-EUSO is designed to observe Ultra-High Energy Cosmic Rays (UHECR)-induced Extensive Air Showers (EAS) by detecting their ultraviolet light tracks 'from above', EUSO-Balloon is a nadir-pointing UV telescope too. With its Fresnel Optics and Photo-Detector Module, the instrument monitors a 50 km ground surface area in a wavelength band of 290-430 nm, collecting series of images at a rate of 400,000 frames/sec. The objectives of the balloon demonstrator are threefold: a) perform a full end-to-end test of a JEM-EUSO prototype consisting of all the main subsystems of the space experiment, b) measure the effective terrestrial UV background, with a spatial and temporal resolution relevant for JEM-EUSO. c) detect tracks of ultraviolet light from near space for the first time. The latter is a milestone in the development of UHECR science, paving the way for any future space-based UHECR observatory. On August 25, 2014, EUSO-Balloon was launched from Timmins Stratospheric Balloon Base (Ontario, Canada) by the balloon division of the French Space Agency CNES. From a float altitude of 38 km, the instrument operated during the entire astronomical night, observing UV-light from a variety of ground-covers and from hundreds of simulated EASs, produced by flashers and a laser during a two-hour helicopter under-flight. [ABSTRACT FROM AUTHOR]

We present a new design for the water Cherenkov detectors that are in use in various cosmic ray observatories. This novel design can provide a significant improvement in the independent measurement of the muonic and electromagnetic component of extensive air showers. From such multi-component data an event by event classification of the primary cosmic ray mass becomes possible. According to popular hadronic interaction models, such as EPOS-LHC or QGSJetII-04, the discriminating power between iron and hydrogen primaries reaches Fisher values of ~ 2 or above for energies in excess of 10 19 eV with a detector array layout similar to that of the Pierre Auger Observatory. [ABSTRACT FROM AUTHOR]

The TUS space experiment is aimed to study the energy spectrum and arrival direction of Ultra High Energy Cosmic Rays (UHECR) at E ~ 10 20 eV . The TUS detector will measure the fluorescence and Cherenkov light radiated by Extensive Air Shower of the UHECR using the optical system that comprises a Fresnel mirror-concentrator of seven modules with a total area of ~ 2 m 2 . The production process of the Fresnel mirror and the method and results of measurement of its optical parameters are presented. [ABSTRACT FROM AUTHOR]

It has been suggested that superheavy charged particles might have been born in primordial bound pairs at the end of cosmic inflation. Such pairs have been proposed as a source of ultrahigh energy cosmic rays (UHECR). We show that primordial bound pairs of magnetic monopoles larger than 10-9 cm quickly thermalise due to the interaction with primordial electron-positron plasma and any such initial primordial concentration is washed out. The final concentration will therefore be defined by their equilibrium abundance. [ABSTRACT FROM AUTHOR]

Abstract: Recent advances in measuring and interpreting cosmic rays from the spectral ankle to the highest energies are briefly reviewed. The prime question at the highest energies is about the origin of the flux suppression observed at . Is this the long-awaited GZK-effect or the exhaustion of sources? The key to answering this question will be provided by the largely unknown mass composition at the highest energies. The high level of isotropy observed even at the highest energies challenges models of a proton-dominated composition if extragalactic magnetic fields are on the order of a few nG or less. We shall discuss the experimental and theoretical progress in the field and the prospects for the next decade. [Copyright &y& Elsevier]

Abstract: While there is some level of consensus on a Galactic origin of cosmic rays up to the knee ( ) and on an extragalactic origin of cosmic rays with energy above ∼1019 eV, the debate on the genesis of cosmic rays in the intermediate energy region has received much less attention, mainly because of the ambiguity intrinsic in defining such a region. The energy range between 1017 eV and ∼1019 eV is likely to be the place where the transition from Galactic to extragalactic cosmic rays takes place. Hence the origin of these particles, though being of the highest importance from the physics point of view, it is also one of the most difficult aspects to investigate. Here I will illustrate some ideas concerning the sites of acceleration of these particles and the questions that their investigation may help answer, including the origin of ultra-high-energy cosmic rays. [Copyright &y& Elsevier]

Abstract: Our understanding of the Galactic magnetic field (GMF) has increased considerably in recent years, while at the same time remaining far from adequate. By way of illustration, the Jansson and Farrar (2012) (JF12) GMF model is described, emphasizing how it is constrained and which features are robust or likely to change, as modeling and constraining data improve. The most urgent requirements for the next phase of modeling are a more realistic model for the relativistic electron distribution (in order to reduce the systematic error associated with interpreting synchrotron data) and a better theoretical understanding of the origin of the large-scale coherent field (in order to develop a better phenomenological parameterization of the field). Even in its current stage of development, the JF12 model allows some important conclusions about UHECR deflections in the GMF to be formulated. [Copyright &y& Elsevier]

Abstract: The Pierre Auger Observatory in Argentina is the largest cosmic ray detector array ever built. Although the construction was completed in 2008, the Observatory has been taking data continuously since January 2004. Its main goal is to measure ultra high energy cosmic rays (UHECRs, energy above 1018 eV) with unprecedented statistics and precision. Measurements of the energy spectrum, chemical composition (including neutrinos and photons) and arrival directions of UHECRs can provide hints for understanding their origin, propagation and interactions. The fluorescence detector of the Pierre Auger Observatory measures the atmospheric depth, X max, where the longitudinal profile of a high energy air shower reaches its maximum. This is sensitive to the nuclear mass composition of the cosmic ray and to the characteristics of the hadronic interactions at very high energy. Due to its hybrid design, the Pierre Auger Observatory also provides independent experimental observables obtained from the surface detector for the study of the shower development. A selection of the Pierre Auger Observatory results on the study of the UHECRs will be presented, focusing on composition results. In particular, the measurements and the different roles of the observables with respect to mass composition will be discussed. [Copyright &y& Elsevier]

Abstract: We present a new simulation engine for fast generation of ultra-high energy cosmic ray data based on parametrizations of common assumptions of UHECR origin and propagation. Implemented are deflections in unstructured turbulent extragalactic fields, energy losses for protons due to photo-pion production and electron-pair production, as well as effects from the expansion of the universe. Additionally, a simple model to estimate propagation effects from iron nuclei is included. Deflections in the Galactic magnetic field are included using a matrix approach with precalculated lenses generated from backtracked cosmic rays. The PARSEC program is based on object oriented programming paradigms enabling users to extend the implemented models and is steerable with a graphical user interface. [Copyright &y& Elsevier]

Abstract: In light of the increasingly heavy UHECR composition at the highest energies, as observed by the Pierre Auger Observatory, the implications of these results on the actual source composition and spectra are investigated. Depending on the maximum energy of the particles accelerated, sources producing hard spectra and/or containing a considerably enhanced heavy component appear a necessary requirement. Consideration is made of two archetypal models compatible with these results. The secondary signatures expected, following the propagation of the nuclear species from source to Earth, are determined for these two example cases. Finally, the effect introduced by the presence of nG extragalactic magnetic fields in collaboration with a large (80Mpc) distance to the nearest source is discussed. [Copyright &y& Elsevier]