Ultra-high-energy cosmic ray

Summary

In astroparticle physics, an ultra-high-energy cosmic ray (UHECR) is a cosmic ray with an energy greater than 1 EeV (1018 electronvolts, approximately 0.16 joules), far beyond both the rest mass and energies typical of other cosmic ray particles. These particles are extremely rare; between 2004 and 2007, the initial runs of the Pierre Auger Observatory (PAO) detected 27 events with estimated arrival energies above 5.7e19eV, that is, about one such event every four weeks in the 3000 km2 area surveyed by the observatory. An extreme-energy cosmic ray (EECR) is an UHECR with energy exceeding 5e19eV (about 8 joule, or the energy of a proton traveling at ≈ 99.99999999999999999998% the speed of light), the so-called Greisen–Zatsepin–Kuzmin limit (GZK limit). This limit should be the maximum energy of cosmic ray protons that have traveled long distances (about 160 million light years), since higher-energy protons would have lost energy over that distance due to scatter

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https://en.wikipedia.org/wiki/Ultra-high-energy_cosmic_ray

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K-EUSO (KLYPVE-EUSO) is a planned orbital mission aimed at studying ultra-high energy cosmic rays (UHECRs) by detecting fluorescence and Cherenkov light emitted by extensive air showers in the nocturnal atmosphere of Earth in the ultraviolet (UV) range. The observatory is being developed within the JEM-EUSO collaboration and is planned to be deployed on the International Space Station after 2025 and operated for at least two years. The telescope, consisting of & SIM;10(5 )independent pixels, will allow a spatial resolution of & SIM;0.6 km on the ground, and, from a 400 km altitude, it will achieve a large and full sky exposure to sample the highest energy range of the UHECR spectrum. We provide a comprehensive review of the current status of the development of the K-EUSO experiment, paying special attention to its hardware parts and expected performance. We demonstrate how results of the K-EUSO mission can complement the achievements of the existing ground-based experiments and push forward the intriguing studies of ultra-high energy cosmic rays, as well as bring new knowledge about other phenomena manifesting themselves in the atmosphere in the UV range.

MDPI2022

An absence of neutrinos associated with cosmic-ray acceleration in gamma-ray bursts

Xiaoxia Bai, Shirit Cohen, Mathieu Ribordy, Matthias Wolf

Very energetic astrophysical events are required to accelerate cosmic rays to above 10(18) electronvolts. GRBs (c-ray bursts) have been proposed as possible candidate sources(1-3). In the GRB 'fireball' model, cosmic-ray acceleration should be accompanied by neutrinos produced in the decay of charged pions created in interactions between the high-energy cosmic-ray protons and gamma-rays(4). Previous searches for such neutrinos found none, but the constraints were weak because the sensitivity was at best approximately equal to the predicted flux(5-7). Here we report an upper limit on the flux of energetic neutrinos associated with GRBs that is at least a factor of 3.7 below the predictions(4,8-10). This implies either that GRBs are not the only sources of cosmic rays with energies exceeding 10(18) electronvolts or that the efficiency of neutrino production is much lower than has been predicted.

2012

The characterization of the cosmogenic neutrino flux would give insights into cosmological source evolution, source spectra and composition at injection, through the partial recovery of the degraded information carried by the ultra high energy cosmic rays. A suitable technique for the detection of these ultra high energy neutrinos relies on the observation of the coherent radio Cherenkov signature emitted by the interaction vertex shower. The detection of the concomitant acoustic pulse is further desirable in order to unambiguously demonstrate the origin of the radiation. Therefore, R&D activities around the design and construction of an acoustic sensor adequate for the detection of neutrino-induced acoustic pulses in ice, coincident with radio Cherenkov signals, down to an energy threshold of about E-v = 10(18) eV, were undertaken. The description of this new digital multi-channel sensor and its performance are presented in this paper. Moreover, the utilization of this sensor as a tool of choice for determining very low environmental acoustic noise levels is discussed. (C) 2011 Elsevier B.V. All rights reserved.

2011