Repository of University of Nova Gorica

Search the repository
A+ | A- | Help | SLO | ENG

Query: search in
search in
search in
search in
* old and bolonia study programme

Options:
  Reset


101 - 110 / 173
First pagePrevious page78910111213141516Next pageLast page
101.
A systematic uncertainty on the energy scale of the Telescope Array fluorescence detectors
J. P. Lundquist, T. Fujii, 2018, published scientific conference contribution

Abstract: The Telescope Array experiment (TA) is the largest cosmic-ray detector in the northern hemi-sphere and consists of a surface detector (SD) array, plus three fluorescence detector (FD) stations overlooking the SD. The large field-of-view of an FD allows for reconstruction of the air-shower development in the atmosphere by imaging ultra-violet fluorescence light from atmospheric nitrogen excited by UHECRs. In estimation of the primary energy it is necessary to add to the calorimetric energy observed by the FD a “missing energy”, meaning the fraction of the primary energy that is not deposited by charged particles in the air. We report on the measurement of the missing energy from observed data collected by the TA FD and TA SD, independently of Monte Carlo simulations, using a technique pioneered by the Pierre Auger Observatory. We also address the effect on the energy scale attributed to fluorescence yield parameters.
Found in: ključnih besedah
Keywords: UHECR, cosmic rays, energy spectrum
Published: 29.04.2020; Views: 1438; Downloads: 53
.pdf Fulltext (4,74 MB)

102.
Energy-position correlation anisotropy of ultra-high energy cosmic rays with Telescope Array Data
J. P. Lundquist, published scientific conference contribution abstract

Abstract: Indication of an energy dependent intermediate-scale anisotropy has been found in the arrival directions of ultra-high energy cosmic rays with energies above 20 EeV in the northern hemisphere, using 7 years of TA surface detector data. The previously reported “hotspot“ excess for E>57 EeV is found to correspond to a deficit, or “coldspot“, of events for energies 2057 EeV has a Li-Ma statistical significance of 4.62σ, and the deficit for energies 20Found in: ključnih besedah
Keywords: UHECR, energy spectrum, anisotropy, magnetic deflection
Published: 29.04.2020; Views: 1491; Downloads: 0
.pdf Fulltext (1,84 MB)

103.
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
Keywords: cosmic rays, high-energy, particle physics, detectors
Published: 29.04.2020; Views: 1631; Downloads: 79
.pdf Fulltext (2,54 MB)

104.
Constraints on the diffuse photon flux with energies above 10^18 eV using the surface detector of the Telescope Array experiment
J. P. Lundquist, R.U. Abbasi, 2018, original scientific article

Abstract: We present the results of the search for ultra-high-energy photons with nine years of data from the Telescope Array surface detector. A multivariate classifier is built upon 16 reconstructed parameters of the extensive air shower. These parameters are related to the curvature and the width of the shower front, the steepness of the lateral distribution function, and the timing parameters of the waveforms sensitive to the shower muon content. A total number of two photon candidates found in the search is fully compatible with the expected background. The 95% CL limits on the diffuse flux of the photons with energies greater than 10^18.0, 10^18.5, 10^19.0, 10^19.5 and 10^20.0 eV are set at the level of 0.067, 0.012, 0.0036, 0.0013, correspondingly.
Found in: ključnih besedah
Summary of found: ...present the results of the search for ultra-high- energy photons with nine years of data from...
Keywords: Ultra-high-energy photons, Telescope array experiment, Extensive air showers
Published: 30.04.2020; Views: 1661; Downloads: 0
.pdf Fulltext (1,33 MB)

105.
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
Keywords: astroparticle physics, cosmic rays, UHECR, energy spectrum
Published: 30.04.2020; Views: 1559; Downloads: 0
.pdf Fulltext (4,40 MB)

106.
The bursts of high energy events observed by the telescope array surface detector
J. P. Lundquist, R.U. Abbasi, 2017, original scientific article

Abstract: The Telescope Array (TA) experiment is designed to detect air showers induced by ultra high energy cosmic rays. The TA ground Surface particle Detector (TASD) observed several short-time bursts of air shower like events. These bursts are not likely due to chance coincidence between single shower events. The expectation of chance coincidence is less than 10^-4 for five-year's observation. We checked the correlation between these bursts of events and lightning data, and found evidence for correlations in timing and position. Some features of the burst events are similar to those of a normal cosmic ray air shower, and some are not. On this paper, we report the observed bursts of air shower like events and their correlation with lightning.
Found in: ključnih besedah
Keywords: High energy radiation, Lightning, Terrestrial gamma-ray flash
Published: 30.04.2020; Views: 1554; Downloads: 0
.pdf Fulltext (1,70 MB)

107.
Energy spectrum of ultra-high energy cosmic rays observed with the Telescope Array using a hybrid technique
J. P. Lundquist, T. Abu-Zayyad, 2015, original scientific article

Abstract: We measure the spectrum of cosmic rays with energies greater than eV with the fluorescence detectors (FDs) and the surface detectors (SDs) of the Telescope Array Experiment using the data taken in our first 2.3-year observation from May 27, 2008 to September 7, 2010. A hybrid air shower reconstruction technique is employed to improve accuracies in determination of arrival directions and primary energies of cosmic rays using both FD and SD data. The energy spectrum presented here is in agreement with our previously published spectra and the HiRes results.
Found in: ključnih besedah
Keywords: Ultra-high energy cosmic rays, Telescope Array, Hybrid spectrum
Published: 30.04.2020; Views: 1659; Downloads: 0
.pdf Fulltext (267,06 KB)

108.
The energy spectrum of ultra-high-energy cosmic rays measured by the Telescope Array FADC fluorescence detectors in monocular mode
J. P. Lundquist, T. Abu-Zayyad, 2013, original scientific article

Abstract: We present a measurement of the energy spectrum of ultra-high-energy cosmic rays performed by the Telescope Array experiment using monocular observations from its two new FADC-based fluorescence detectors. After a short description of the experiment, we describe the data analysis and event reconstruction procedures. Since the aperture of the experiment must be calculated by Monte Carlo simulation, we describe this calculation and the comparisons of simulated and real data used to verify the validity of the aperture calculation. Finally, we present the energy spectrum calculated from the merged monocular data sets of the two FADC-based detectors, and also the combination of this merged spectrum with an independent, previously published monocular spectrum measurement performed by Telescope Array’s third fluorescence detector [T. Abu-Zayyad et al., The energy spectrum of Telescope Array’s middle drum detector and the direct comparison to the high resolution fly’s eye experiment, Astroparticle Physics 39 (2012) 109-119, http://dx.doi.org/10.1016/j.astropartphys.2012.05.012, Available from: ]. This combined spectrum corroborates the recently published Telescope Array surface detector spectrum [T. Abu-Zayyad, et al., The cosmic-ray energy spectrum observed with the surface detector of the Telescope Array experiment, ApJ 768 (2013) L1, http://dx.doi.org/10.1088/2041-8205/768/1/L1, Available from: ] with independent systematic uncertainties.
Found in: ključnih besedah
Keywords: UHECR, Energy spectrum, Fluorescence, Monocular
Published: 19.05.2020; Views: 1441; Downloads: 0
.pdf Fulltext (926,83 KB)

109.
The surface detector array of the Telescope Array experiment
J. P. Lundquist, T. Abu-Zayyad, 2012, original scientific article

Abstract: The Telescope Array (TA) experiment, located in the western desert of Utah, USA, is designed for the observation of extensive air showers from extremely high energy cosmic rays. The experiment has a surface detector array surrounded by three fluorescence detectors to enable simultaneous detection of shower particles at ground level and fluorescence photons along the shower track. The TA surface detectors and fluorescence detectors started full hybrid observation in March, 2008. In this article we describe the design and technical features of the TA surface detector.
Found in: ključnih besedah
Summary of found: ...of extensive air showers from extremely high energy cosmic rays. The experiment has a surface...
Keywords: Ultra-high energy cosmic rays, Telescope Array experiment, Extensive air shower array
Published: 19.05.2020; Views: 1503; Downloads: 0
.pdf Fulltext (1,81 MB)

110.
New air fluorescence detectors employed in the Telescope Array experiment
J. P. Lundquist, H. Tokuno, 2012, original scientific article

Abstract: Since 2007, the Telescope Array (TA) experiment, based in Utah, USA, has been observing ultra high energy cosmic rays to understand their origins. The experiment includes a surface detector (SD) array and three fluorescence detector (FD) stations. The FD stations, installed surrounding the SD array, measure the air fluorescence light emitted from extensive air showers (EASs) for precise determination of their energies and species. The detectors employed at one of the three FD stations were relocated from the High Resolution Fly's Eye (HiRes) experiment. At the other two stations, newly designed detectors were constructed for the TA experiment. An FD consists of a primary mirror and a camera equipped with photomultiplier tube pixels. To obtain the EAS parameters with high accuracy, understanding the FD optical characteristics is important. In this paper, we report the characteristics and installation of the new FDs and the performances of the FD components. The results of the monitored mirror reflectance during the observation time are also described in this report.
Found in: ključnih besedah
Summary of found: ...Utah, USA, has been observing ultra high energy cosmic rays to understand their origins. The...
Keywords: Ultra high energy cosmic rays, Extensive air showers, Air fluorescence light detectors
Published: 19.05.2020; Views: 1371; Downloads: 0
.pdf Fulltext (1,44 MB)

Search done in 0 sec.
Back to top