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Energy response of ISS-CREAM calorimeter with attenuation effect
J. P. Lundquist, H.G. Zhang, 2020, other component parts

Abstract: The NASA mission, Cosmic Ray Energetic And Mass experiment for the International Space Station (ISS-CREAM) is to measure individual cosmic-ray particle energy spectra from protons to iron nuclei, with an energy range from ~1 TeV to the so-called "knee", near 1015eV. Energies of cosmic-ray particles are measured from electromagnetic showers induced by particles in the calorimeter. As a pioneer mission, the balloon-borne CREAM instrument has successfully flown seven times over the Antarctica for a cumulative exposure of 191 days. The CREAM calorimeter has shown sufficient capability to measure energies of cosmic-ray particles by capturing the electromagnetic shower profile within the interested energy range. The ISS-CREAM calorimeter is expected to have a similar performance and, before it was launched, an engineering-unit calorimeter was shipped to CERN for a full beam test. The full performance test includes position, energy, and angle scans of electron and pion beams together with a high voltage scan for calibration and characterization. In addition to the regular analysis for performance test, we also applied an additional step to generate the universal energy responses by correcting the attenuation effect in the calorimeter readout. The general energy responses could be obtained after shifting the incident beam positions to a reference position near the center of the calorimeter, which provided improved energy resolutions. The result of this analysis will be used to determine the incident energies of the cosmic-ray particles in the flight data.
Found in: ključnih besedah
Summary of found: ...cosmic rays, high-energy, particle physics, detectors...
Keywords: cosmic rays, high-energy, particle physics, detectors
Published: 29.04.2020; Views: 2149; Downloads: 126
.pdf Fulltext (2,54 MB)

The Cosmic Ray Energy Spectrum between 2 PeV and 2 EeV Observed with the TALE Detector in Monocular Mode
J. P. Lundquist, R.U. Abbasi, 2018, original scientific article

Abstract: We report on a measurement of the cosmic ray energy spectrum by the Telescope Array Low-Energy Extension (TALE) air fluorescence detector (FD). The TALE air FD is also sensitive to the Cherenkov light produced by shower particles. Low-energy cosmic rays, in the PeV energy range, are detectable by TALE as Cherenkov events. Using these events, we measure the energy spectrum from a low energy of ~2 PeV to an energy greater than 100 PeV. Above 100 PeV, TALE can detect cosmic rays using air fluorescence. This allows for the extension of the measurement to energies greater than a few EeV. In this paper, we describe the detector, explain the technique, and present results from a measurement of the spectrum using ~1000 hr of observation. The observed spectrum shows a clear steepening near 10^17.1 eV, along with an ankle-like structure at 10^16.2 eV. These features present important constraints on the origin of galactic cosmic rays and on propagation models. The feature at 10^17.1 eV may also mark the end of the galactic cosmic ray flux and the start of the transition to extragalactic sources.
Found in: ključnih besedah
Summary of found: ...astroparticle physics, cosmic rays, UHECR, energy spectrum...
Keywords: astroparticle physics, cosmic rays, UHECR, energy spectrum
Published: 30.04.2020; Views: 1921; Downloads: 0
.pdf Fulltext (4,40 MB)

Study of muons from ultrahigh energy cosmic ray air showers measured with the Telescope Array experiment
J. P. Lundquist, R.U. Abbasi, 2018, original scientific article

Abstract: One of the uncertainties in the interpretation of ultrahigh energy cosmic ray data comes from the hadronic interaction models used for air shower Monte Carlo (MC) simulations. The number of muons observed at the ground from ultrahigh energy cosmic ray–induced air showers is expected to depend upon the hadronic interaction model. One may therefore test the hadronic interaction models by comparing the measured number of muons with the MC prediction. In this paper, we present the results of studies of muon densities in ultrahigh energy extensive air showers obtained by analyzing the signal of surface detector stations which should have high muon purity. The muon purity of a station will depend on both the inclination of the shower and the relative position of the station. In seven years’ data from the Telescope Array experiment, we find that the number of particles observed for signals with an expected muon purity of ∼65% at a lateral distance of 2000 m from the shower core is 1.72± 0.10(stat)±0.37(syst) times larger than the MC prediction value using the QGSJET II-03 model for proton-induced showers. A similar effect is also seen in comparisons with other hadronic models such as QGSJET II-04, which shows a 1.67±0.10±0.36 excess. We also studied the dependence of these excesses on lateral distances and found a slower decrease of the lateral distribution of muons in the data as compared to the MC, causing larger discrepancy at larger lateral distances.
Found in: ključnih besedah
Keywords: UHECR, cosmic rays, muons, particle physics
Published: 30.04.2020; Views: 1781; Downloads: 0
.pdf Fulltext (2,16 MB)

Search for correlations between the arrival directions of IceCube neutrino events and ultrahigh-energy cosmic rays detected by the Pierre Auger Observatory and the Telescope Array
J. P. Lundquist, M. G. Aartsen, 2016, original scientific article

Abstract: This paper presents the results of different searches for correlations between very high-energy neutrino candidates detected by IceCube and the highest-energy cosmic rays measured by the Pierre Auger Observatory and the Telescope Array. We first consider samples of cascade neutrino events and of high-energy neutrino-induced muon tracks, which provided evidence for a neutrino flux of astrophysical origin, and study their cross-correlation with the ultrahigh-energy cosmic ray (UHECR) samples as a function of angular separation. We also study their possible directional correlations using a likelihood method stacking the neutrino arrival directions and adopting different assumptions on the size of the UHECR magnetic deflections. Finally, we perform another likelihood analysis stacking the UHECR directions and using a sample of through-going muon tracks optimized for neutrino point-source searches with sub-degree angular resolution. No indications of correlations at discovery level are obtained for any of the searches performed. The smallest of the p-values comes from the search for correlation between UHECRs with IceCube high-energy cascades, a result that should continue to be monitored.
Found in: ključnih besedah
Summary of found: ...UHECR, cosmic rays, neutrinos, multi-messenger physics, anisotropy...
Keywords: UHECR, cosmic rays, neutrinos, multi-messenger physics, anisotropy
Published: 30.04.2020; Views: 1853; Downloads: 0
.pdf Fulltext (2,49 MB)

PHYSICS II - Exercises
Jurij Urbančič, other educational material

Abstract: The following script is the first part of selected exercises and examples from the topics of Hydrostatics and Hydrodynamics. They were collected during the academic year 2019/20 when I was holding Physics II tutorials for the study program Physics and Astrophysics I. level within the School of Science at the University of Nova Gorica. The source material I used is given in the Bibliography at the end. Hopefully, these exercise fill help in providing a more in-depth understanding of physical phenomena discussed during the lectures.
Found in: ključnih besedah
Keywords: Hydrostatics, Hydrodynamics, Physics 2
Published: 07.05.2020; Views: 2191; Downloads: 0
.pdf Fulltext (404,17 KB)

Correlations of the arrival directions of ultra-high energy cosmic ray with extragalactic objects as observed by the telescope array experiment
J. P. Lundquist, T. Abu-Zayyad, 2013, original scientific article

Abstract: We search for correlations between the positions of extragalactic objects and the arrival directions of ultra-high energy cosmic rays (UHECRs) with primary energy E ≥ 40 EeV as observed by the surface detector array of the Telescope Array (TA) experiment during the first 40 months of operation. We examine several public astronomical object catalogs, including the Veron-Cetty and Veron catalog of active galactic nuclei. We count the number of TA events correlated with objects in each catalog as a function of three parameters: the maximum angular separation between a TA event and an object, the minimum energy of the events, and the maximum redshift of the objects. We determine the combination of these parameters that maximizes the correlations, and we calculate the probability of having the same levels of correlations from an isotropic distribution of UHECR arrival directions. No statistically significant correlations are found when penalties for scanning over the above parameters and for searching in several catalogs are taken into account.
Found in: ključnih besedah
Summary of found: ...acceleration of particles, astroparticle physics, cosmic rays...
Keywords: acceleration of particles, astroparticle physics, cosmic rays
Published: 19.05.2020; Views: 2083; Downloads: 112
.pdf Fulltext (779,07 KB)

Search for anisotropy of ultrahigh energy cosmic rays with the Telescope Array experiment
J. P. Lundquist, T. Abu-Zayyad, 2012, original scientific article

Abstract: We study the anisotropy of Ultra-High Energy Cosmic Ray (UHECR) events collected by the Telescope Array (TA) detector in the first 40 months of operation. Following earlier studies, we examine event sets with energy thresholds of 10 EeV, 40 EeV, and 57 EeV. We find that the distributions of the events in right ascension and declination are compatible with an isotropic distribution in all three sets. We then compare with previously reported clustering of the UHECR events at small angular scales. No significant clustering is found in the TA data. We then check the events with E > 57 EeV for correlations with nearby active galactic nuclei. No significant correlation is found. Finally, we examine all three sets for correlations with the large-scale structure (LSS) of the universe. We find that the two higher-energy sets are compatible with both an isotropic distribution and the hypothesis that UHECR sources follow the matter distribution of the universe (the LSS hypothesis), while the event set with E > 10 EeV is compatible with isotropy and is not compatible with the LSS hypothesis at 95% CL unless large deflection angles are also assumed. We show that accounting for UHECR deflections in a realistic model of the Galactic magnetic field can make this set compatible with the LSS hypothesis.
Found in: ključnih besedah
Summary of found: ...acceleration of particles, astroparticle physics, cosmic rays, magnetic fields, methods: statistical, relativistic...
Keywords: acceleration of particles, astroparticle physics, cosmic rays, magnetic fields, methods: statistical, relativistic processes
Published: 19.05.2020; Views: 2078; Downloads: 0
.pdf Fulltext (1,04 MB)

Evidence for a Supergalactic Structure of Magnetic Deflection Multiplets of Ultra-High Energy Cosmic Rays
J. P. Lundquist, R. Abbasi, 2020, original scientific article

Abstract: Evidence for a large-scale supergalactic cosmic ray multiplet (arrival directions correlated with energy) structure is reported for ultra-high energy cosmic ray (UHECR) energies above 10^19 eV using seven years of data from the Telescope Array (TA) surface detector and updated to 10 years. Previous energy-position correlation studies have made assumptions regarding magnetic field shapes and strength, and UHECR composition. Here the assumption tested is that, since the supergalactic plane is a fit to the average matter density of the local Large Scale Structure (LSS), UHECR sources and intervening extragalactic magnetic fields are correlated with this plane. This supergalactic deflection hypothesis is tested by the entire field-of-view (FOV) behavior of the strength of intermediate-scale energy-angle correlations. These multiplets are measured in spherical cap section bins (wedges) of the FOV to account for coherent and random magnetic fields. The structure found is consistent with supergalactic deflection, the previously published energy spectrum anisotropy results of TA (the hotspot and coldspot), and toy-model simulations of a supergalactic magnetic sheet. The seven year data post-trial significance of this supergalactic structure of multiplets appearing by chance, on an isotropic sky, is found by Monte Carlo simulation to be 4.19σ. The ten years of data post-trial significance is 4.09σ. Furthermore, the starburst galaxy M82 is shown to be a possible source of the TA Hotspot, and an estimate of the supergalactic magnetic field using UHECR measurements is presented.
Found in: ključnih besedah
Summary of found: ...astroparticle physics, cosmic rays, UHECR, supergalactic plane, multiplets, magnetic...
Keywords: astroparticle physics, cosmic rays, UHECR, supergalactic plane, multiplets, magnetic deflection, large-scale structure of universe
Published: 19.05.2020; Views: 1922; Downloads: 0
.pdf Fulltext (4,40 MB)

Giustina Selvelli, original scientific article

Abstract: In this paper, I focus on the role played by material objects in the evocation of a specific imaginary of the recent past (mainly the 1970s and 1980s) in the literary works of Bulgarian writer Georgi Gospodinov (in the novels “The Physics of Sorrow” and “Natural Novel”) and of Turkish novelist Orhan Pamuk (in “The Museum of Innocence”). I analyze the presence of feelings of melancholy and loss accompanied by a fixation on objects in the fictional works and describe their possible overcoming through an externalization in the form of museum exhibitions in the city of Sofia and Istanbul such as the “Inventory depository of Socialism” and the “Museum of Innocence”. By viewing objects as actors capable of creating meaningful social networks, I consider their use in the narration of personal and collective histories and their transformation as powerful symbols of a bygone era.
Found in: ključnih besedah
Summary of found: ...writer Georgi Gospodinov (in the novels “The Physics of Sorrow” and “Natural Novel”) and of...
Keywords: melancholy, objects, socialism, Georgi Gospodinov, Istanbul, Orhan Pamuk, Physics of Sorrow, The Museum of Innocence
Published: 19.06.2020; Views: 2001; Downloads: 0
.pdf Fulltext (341,59 KB)

On the GeV Emission of the Type I BdHN GRB 130427A
Laura Beccera, She Sheng Xue, Yu Wang, Narek Sahakyan, Mile Karlica, Yen-Chen Chen, Simonetta Filippi, Christian Cherubini, Carlo Luciano Bianco, Jorge Armando Rueda, Rahim Moradi, Remo Ruffini, 2019, original scientific article

Abstract: We propose that the inner engine of a type I binary-driven hypernova (BdHN) is composed of Kerr black hole (BH) in a non-stationary state, embedded in a uniform magnetic field B_0 aligned with the BH rotation axis and surrounded by an ionized plasma of extremely low density of 10^−14 g cm−3. Using GRB 130427A as a prototype, we show that this inner engine acts in a sequence of elementary impulses. Electrons accelerate to ultrarelativistic energy near the BH horizon, propagating along the polar axis, θ = 0, where they can reach energies of ~10^18 eV, partially contributing to ultrahigh-energy cosmic rays. When propagating with $\theta \ne 0$ through the magnetic field B_0, they produce GeV and TeV radiation through synchroton emission. The mass of BH, M = 2.31M ⊙, its spin, α = 0.47, and the value of magnetic field B_0 = 3.48 × 10^10 G, are determined self consistently to fulfill the energetic and the transparency requirement. The repetition time of each elementary impulse of energy ${ \mathcal E }\sim {10}^{37}$ erg is ~10^−14 s at the beginning of the process, then slowly increases with time evolution. In principle, this "inner engine" can operate in a gamma-ray burst (GRB) for thousands of years. By scaling the BH mass and the magnetic field, the same inner engine can describe active galactic nuclei.
Found in: ključnih besedah
Summary of found: hole physics, binaries, gamma-ray burst, neutron stars, supernovae, Astrophysics...
Keywords: black hole physics, binaries, gamma-ray burst, neutron stars, supernovae, Astrophysics - High Energy Astrophysical Phenomena
Published: 20.07.2020; Views: 1984; Downloads: 0
.pdf Fulltext (1,09 MB)

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