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51.
TA SD analysis for inclined air showers
K. Takahashi, Jon Paul Lundquist, 2023, published scientific conference contribution

Abstract: The origin of UHECRs is an open question which is complicated due to not very well-known deflections of the charged particles in Galactic and intergalactic magnetic fields. Finding the EeV neutrinos from astronomical sources will be a key to solve the problem of the origin. EeV neutrinos are expected to produce extensive air showers which are observable by the current operational air shower arrays. To search for neutrino-induced showers, it is important to increase both the interaction probability and background rejection power in the analysis of the inclined showers. We study a reconstruction method of the Telescope Array surface detector (TA SD) data for the neutrino-induced inclined air showers. The prime target is to improve the angular resolution for the astronomical objects. In this contribution, we present the detail of analysis method, angular resolution and total exposure of TA SD for neutrinos from the astronomical objects as a function of the declination.
Keywords: Telescope Array, indirect detection, surface detection, ground array, ultra-high energy, cosmic rays, inclined showers, neutrinos
Published in RUNG: 09.10.2023; Views: 507; Downloads: 5
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52.
Measurement of the cosmic ray energy spectrum with the TA×4 SD array
Kozo Fujisue, R. U. Abbasi, Y. Abe, T. Abu-Zayyad, M. Allen, Yasuhiko Arai, R. Arimura, E. Barcikowski, J. W. Belz, Douglas R. Bergman, 2023, published scientific conference contribution

Abstract: The TA×4 experiment aims to better understand the origin and nature of ultra-high energy cosmic rays (UHECRs) by expanding the observation area of the Telescope Array (TA) experiment by a factor of 4. This expansion will increase the statistics of UHECR events with energies greater than 10^19.5 eV. The SD, which means the additionally deployed surface detectors (SD) for the TA×4 experiment, has been collecting data since 2019, and the analysis of this data is currently underway. In this presentation, we will report comparisons between the Monte Carlo simulation and the data obtained by the TA×4 SD array and highlight the agreement between the two. We will also report on the UHECR energy spectrum observed by the TA×4 SD array from October 2019 to September 2022.
Keywords: Telescope Array, TAx4, indirect detection, surface detection, ground array, ultra-high energy, cosmic rays, energy spectrum
Published in RUNG: 09.10.2023; Views: 523; Downloads: 7
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53.
Search for EeV photon-induced events at the Telescope Array
I. Kharuk, R. U. Abbasi, Y. Abe, T. Abu-Zayyad, M. Allen, Yasuhiko Arai, R. Arimura, E. Barcikowski, J. W. Belz, Douglas R. Bergman, 2023, published scientific conference contribution

Abstract: We report on the updated results on the search for photon-like-induced events in the data, collected by Telescope Array's Surface Detectors during the last 14 years. In order to search for photon-like-induced events, we trained a neural network on Monte-Carlo simulated data to distinguish between the proton-induced and photon-induced air showers. Both reconstructed composition-sensitive parameters and raw signals registered by the Surface Detectors are used as input data for the neural network. The classification threshold was optimized to provide the strongest possible constraint on the photons' flux.
Keywords: Telescope Array, indirect detection, surface detection, ground array, ultra-high energy, cosmic rays, photons, neural network, machine learning
Published in RUNG: 09.10.2023; Views: 622; Downloads: 6
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54.
Systematic uncertainty in the analysis of the TA fluorescence detector from fluorescence yield models
Kohei Komori, R. U. Abbasi, Y. Abe, T. Abu-Zayyad, M. Allen, Yasuhiko Arai, R. Arimura, E. Barcikowski, J. W. Belz, Douglas R. Bergman, 2023, published scientific conference contribution

Abstract: Ultra-high energy cosmic rays have been observed by various experiments such as Telescope Array (TA) and the Pierre Auger Observatory (Auger). There are differences in the energy spectra measured by TA and Auger. One reason for this difference is systematic uncertainty in the energy determination. The fluorescence yield model, which consists of fluorescence emission efficiencies and spectra, is one of the most significant components of this systematic uncertainty. Fluorescence emission efficiencies and spectra have been measured in various experiments, and different measurements are currently used to determine the energy of the TA and Auger experiments. In this study, we estimate the influence of the fluorescence yield model on the systematic uncertainty in the energy determination of the TA fluorescence detector.
Keywords: Telescope Array, TAx4, indirect detection, fluorescence detection, fluorescence yield, ultra-high energy, cosmic rays, energy uncertainty
Published in RUNG: 09.10.2023; Views: 582; Downloads: 5
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55.
Monocular and hybrid analysis for TA×4 fluorescence detectors
Yuki Kusumori, R. U. Abbasi, Y. Abe, T. Abu-Zayyad, M. Allen, Yasuhiko Arai, R. Arimura, E. Barcikowski, J. W. Belz, Douglas R. Bergman, 2023, published scientific conference contribution

Abstract: The TA×4 project is an extension of the Telescope Array (TA) experiment, aimed at clarifying the origin of the highest energy cosmic rays. It has deployed 4 fluorescence detectors (FDs) and 130 surface detectors (SDs) at the northeast lobe of the original TA array and 8 FDs and 127 SDs at the southeast lobe of the original TA array, expanding the detection area about four times larger than the TA experiment. This expansion enables us to sample larger data. The TA×4 has been collecting data to obtain solid evidence of the excess of events in the arrival direction distribution, known as the TA hotspot, reported in 2014 by the TA experiment. The north and south observations began in 2018 and 2019, respectively, and are ongoing except for a hiatus from February to June 2020 due to the COVID-19 pandemic. In this presentation, we will report the details of TA×4 FD monocular analysis.
Keywords: Telescope Array, TAx4, indirect detection, hybrid detection, ground array, fluorescence detection, ultra-high energy, cosmic rays, energy spectrum, composition
Published in RUNG: 09.10.2023; Views: 558; Downloads: 6
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56.
A study of the systematic effects on the energy scale for the measurement of UHECR spectrum by the TA SD array
Keitaro Fujita, R. U. Abbasi, Y. Abe, T. Abu-Zayyad, M. Allen, Yasuhiko Arai, R. Arimura, E. Barcikowski, J. W. Belz, Jon Paul Lundquist, 2023, published scientific conference contribution

Abstract: We evaluated the systematic deviation of energy scales for the energy spectrum of the highest energy cosmic rays observed by the Telescope Array Surface Detector array due to differences in atmospheric fluorescence yield and missing energy estimation. The energy dependence on the energy scales is also investigated and observationally confirmed by the constant intensity cut method analysis. The results of these studies will be presented.
Keywords: Telescope Array, indirect detection, surface detection, ground array, fluorescence detection, ultra-high energy, cosmic rays, energy spectrum, fluorescence yield, missing energy, systematics
Published in RUNG: 09.10.2023; Views: 606; Downloads: 4
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57.
Cosmic ray mass composition measurement with the TALE hybrid detector
K. Fujita, Jon Paul Lundquist, 2022, published scientific conference contribution

Abstract: We report on the cosmic ray mass composition measured by the Telescope Array Low-energy Extension (TALE) hybrid detector. The TALE detector consists of a Fluorescence Detector (FD) station with 10 FD telescopes located at the TA Middle Drum FD Station (itself made up of 14 FD telescopes), and a Surface Detector (SD) array of scintillation counters. The SD array consists of 40 counters with 400 m spacing and 40 counters with 600 m spacing. The FD station, with a total of 24 telescopes, overlooks the SD array and provides sky coverage with an elevation angle range of 3∘ to 59∘. In this contribution, we will present the latest result of the cosmic ray mass composition measurement in the energy range from 10^16.5 eV to 10^18.5 eV using almost 5 years of TALE hybrid data.
Keywords: Telescope Array, TALE, low energy extension, indirect detection, hybrid detection, ground array, infill array, fluorescence detection, cerenkov light, ultra-high energy, cosmic rays, composition
Published in RUNG: 09.10.2023; Views: 532; Downloads: 6
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58.
Interpretation of the CALET Electron+Positron Spectrum concerning Dark Matter Signatures
Holger Motz, Yoichi Asaoka, Saptashwa Bhattacharyya, 2019, original scientific article

Abstract: CALET (CALorimetric Electron Telescope) is in operation on the ISS since October 2015 and directly measures the electron+positron cosmic-ray spectrum up into the TeV-region with fine energy resolution and good proton rejection. Interpretations of the latest results published in [O. Adriani et al. PRL 120, 261102] regarding Dark Matter signatures are presented. Limits on annihilation and decay of Dark Matter were calculated based on an analytic parametrization of the local electron and positron spectra, including a term representing the flux from nearby pulsars as the extra electron-positron-pair source responsible for the positron excess, which is fitted to CALET data and positron flux/fraction data of AMS-02. The expected flux from Dark Matter is calculated with PYTHIA and DRAGON and added to the parametrization with increasing scale factor until reaching 95%CL exclusion, returning a limit on the annihilation cross-section or lifetime. By treating systematic uncertainties with known energy dependence as corrections to the fit function, limits were improved compared to all-random errors. Structures appear in the spectrum, which have been investigated as potential Dark Matter signatures by looking for an improvement of the fit quality with addition of flux from Dark Matter. Thereby, annihilation of ~350 GeV or decay of ~700 GeV Dark Matter to electron-positron pairs is identified as a possible explanation of a step-like structure around 350 GeV. The significance of this signature, Dark Matter explanations of other spectral features and possible astrophysical alternatives are discussed.
Keywords: Cosmic-rays, Dark Matter, CALET
Published in RUNG: 05.10.2023; Views: 617; Downloads: 5
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59.
Searching for Anisotropy in Electron+Positron Cosmic Rays with CALET
Holger Motz, Yoichi Asaoka, Shoji Torii, Saptashwa Bhattacharyya, 2017, original scientific article

Abstract: The ISS-based Calorimetric Electron Telescope (CALET) is directly measuring the energy spectrum and direction distribution of electron+positron cosmic-rays up to 20 TeV. A main goal of CALET is to identify a signature of a nearby supernova remnant (SNR) in electron+positron cosmic-rays. The Vela SNR has the highest potential to cause a spectral feature in the TeV region and/or a detectable anisotropy. Using the numerical cosmic-ray propagation code DRAGON, the spectrum and expected anisotropy of the Vela SNR together with background from more distant SNR was calculated depending on injection and propagation conditions. The results of these calculations were used to simulate CALET event sky-maps on which several analysis methods were employed to estimate the CALET sensitivity. Assuming that there is no anisotropy, the expected limits on the dipole amplitude from an all-sky search were calculated as a function of the selected energy range and the shape of the predicted spectra. However for the detection of a dipole anisotropy, the direction towards Vela is predetermined, and sensitivity is strongly boosted by a directed search. It is shown that with this method, CALET has a significant probability to identify an anisotropy signature from Vela. As it may disturb the Vela signature, the contribution to the local cosmic-ray anisotropy from several other nearby SNR and pulsars, as well as from the general source distribution in the galaxy was studied. It was found that Vela is expected to dominate and have a detectable signature, though there is some influence from other sources on direction and strength of the anisotropy. Furthermore, the implications of detecting an dipole anisotropy directed towards Vela for the local propagation parameters, such as the diffusion coefficient, are explained.
Keywords: cosmic-rays, CALET, cosmic-ray propagation
Published in RUNG: 05.10.2023; Views: 507; Downloads: 4
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60.
Telescope Array Cloud Ranging Test
T. Okuda, Jon Paul Lundquist, 2022, published scientific conference contribution

Abstract: The Telescope Array (TA) experiment detects air-showers induced by ultra high energy cosmic rays. The TA atmospheric Fluorescence telescopic Detector(TAFD) observes cosmic ray airshower, which is incident very far from the telescope. The observation does not take place in overcast night. However, the cloud status changes quickly and sometimes there are some isolated clouds. If the cloud is behind the airshower as viewed from the TAFD, the cloud presents no problem for airshower reconstruction. However if the cloud obscures the airshower, it does create a problem for airshower reconstruction. The problematic event can be rejected by airshower profile at reconstruction. However, the estimation of exposure with isolated cloud is difficult. And it should be affected more at higher energy event with relatively further from the telescope, which is lower statistics and more important for the ultra high energy cosmic ray physics. Therefore, to test the method for evaluating the correction of exposure, we installed stereo cloud cameras near one of FD sites. I report the status of the study of the Telescope Array Cloud Ranging Test.
Keywords: Telescope Array, indirect detection, fluorescence detection, cerenkov light, ultra-high energy, cosmic rays, atmosphere, cloud detection, exposure, air shower reconstruction
Published in RUNG: 04.10.2023; Views: 736; Downloads: 7
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