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Abstract: Fanaroff-Riley (FR) 0 radio galaxies compose a new class of radio galaxies, which are usually weaker but much more numerous than the well-established class of FR 1 and FR 2 galaxies. The latter classes have been proposed as sources of the ultra-high-energy cosmic rays (UHECRs) with energies reaching up to eV. Based on this conjecture, the possibility of UHECR acceleration and survival in an FR 0 source environment is examined in this work. In doing so, an average spectral energy distribution (SED) based on data from the FR 0 catalog (FR0CAT) is compiled. The resulting photon fields are used as targets for UHECRs, which suffer from electromagnetic pair production, photo-disintegration, photo-meson production losses, and synchrotron radiation. Multiple mechanisms are discussed to assess the UHECR acceleration probability, including Fermi-I order and gradual shear accelerations, and particle escape from the source region. This work shows that in a hybrid scenario, combining Fermi and shear accelerations, FR 0 galaxies can contribute to the observed UHECR flux, as long as where shear acceleration starts to dominate over escape. Even in less optimistic scenarios, FR 0s can be expected to contribute to the cosmic-ray flux between the knee and the ankle. Our results are relatively robust with respect to the realized magnetic turbulence model and the speed of the accelerating shocks.
Found in: osebi
Keywords: acceleration of particles, nonthermal radiation mechanisms, jets, active galaxies, cosmic rays
Published: 05.02.2021; Views: 1216; Downloads: 0
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Abstract: The Cosmic Ray Energetic And Mass for the International Space Station (ISS-CREAM) experiment is designed for precision measurements of energy spectra and elemental composition of cosmic rays. It was launched and installed on the ISS in August 2017. The Silicon Charge Detector (SCD), placed at the top of the ISS-CREAM payload, consists of 4 layers with a total of 10,752 silicon pixels which have 1.37 × 1.57 cm^2 size each. Each layer is arranged in such a fashion that its active detection area of 78 × 74 cm^2 is free of any dead area. The SCD 4-layer configuration was chosen to achieve the best precision in measuring the charge of cosmic rays from proton to iron nuclei with a charge resolution of 0.1 − 0.3e. We will present its on-orbit performance and operation status on the ISS since the launch.
Found in: osebi
Keywords: instrumentations, high energy cosmic rays, particle detectors
Published: 08.02.2021; Views: 1068; Downloads: 0
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Abstract: Cosmic Ray Energetics And Mass for the International Space Station (ISS-CREAM) experiment is designed to study the composition and energy spectra of cosmic-ray particles from 10^12 to 10^15 eV. ISS-CREAM was launched and deployed to the ISS in August 2017. The ISS-CREAM payload employs a Silicon Charge Detector for charge measurements, Top and Bottom Counting Detector for electron-hadron separation and a low-energy trigger, a Boronated Scintillator Detector for additional electron-hadron separation, and a Calorimeter (CAL) for en-ergy measurements and a high-energy trigger. The CAL is constructed of 20 layers of tungsten plates interleaved with scintillating fiber ribbons read out by hybrid-photodiodes (HPDs) and densified carbon targets. Each CAL layer is made of 3.5 mm (1 X_0) thick tungsten plates alter-nating with fifty 0.5 mm thick and 1 cm wide scintillating fiber ribbons. Consecutive layers of fiber ribbons are installed orthogonal to each other. Energy deposition in the CAL determines the particle energy and provides tracking information to determine which segment(s) of the charge detectors to use for the charge measurement. Tracking for showers is accomplished by extrapolating each shower axis back to the charge detectors. The performance of the ISS-CREAM CAL during flight is presented.
Found in: osebi
Keywords: instrumentations, high energy cosmic rays, particle detectors
Published: 08.02.2021; Views: 986; Downloads: 0
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Abstract: To obtain direct measurements of the muon content of extensive air showers with energy above 10[sup]16.5 eV, the Pierre Auger Observatory is currently being equipped with an underground muon detector (UMD), consisting of 219 10 m[sup]2-modules, each segmented into 64 scintillators coupled to silicon photomultipliers (SiPMs). Direct access to the shower muon content allows for the study of both of the composition of primary cosmic rays and of high-energy hadronic interactions in the forward direction. As the muon density can vary between tens of muons per m[sup]2 close to the intersection of the shower axis with the ground to much less than one per m[sup]2 when far away, the necessary broad dynamic range is achieved by the simultaneous implementation of two acquisition modes in the read-out electronics: the binary mode, tuned to count single muons, and the ADC mode, suited to measure a high number of them. In this work, we present the end-to-end calibration of the muon detector modules: first, the SiPMs are calibrated by means of the binary channel, and then, the ADC channel is calibrated using atmospheric muons, detected in parallel to the shower data acquisition. The laboratory and field measurements performed to develop the implementation of the full calibration chain of both binary and ADC channels are presented and discussed. The calibration procedure is reliable to work with the high amount of channels in the UMD, which will be operated continuously, in changing environmental conditions, for several years.
Found in: osebi
Keywords: ultra-high energy cosmic rays, extensive air showers (EAS), EAS muonic component, Pierre Auger Observatory, underground muon detector, detector calibration
Published: 14.04.2021; Views: 1058; Downloads: 69
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Found in: osebi
Keywords: Sprotno zajemanje podatkov, kontrolni sistemi, algoritmi, baze podatkov, Observatorij Pierre Auger
Published: 21.07.2021; Views: 822; Downloads: 25
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